I cannot open Photoshop CS with El Capitan, can anybody help?

There's no way anyone can help. Photoshop CS1 is simply too old to run on El Capitan.

You can either restore to your previous OS from your time machine backup. You did backup before upgrading? Or buy an updated version of Photoshop.

Reports from users about legacy Adobe products running on versions of OS X are included on these forums with varying degrees of success, however what you want to do is not possible. If you need an Adobe product that is compatible with the OS you are using see this URL for what Adobe claims is their matrix as to what will work with what (with the knowledge it is not written in stone and they want you to buy Creative Cloud)

https://helpx.adobe.com/photoshop/system-requirements.html

as ACM points out if you want CS1 to work you need an earlier version of the OS. If you are trying to do that on a Mac that was released after that OS there is no legal way to do that unless you own that OS and a license prior to the install and the 3rd party virtualization software to do so since Apple does not allow you to install a previous mac OS to their computers by design. So unless you have an older computer and a time machine backup you are looking at a project to get this software to run.

If you are running on an 8 year old computer you can use the disks that came with your computer to wipe your current system (or replace the drive, or use an external) and reinstall an older OS. If this is your course of action it is highly recommend you backup with time machine beforehand, keep in mind other software; especially web browsers and web components will not be updatable in these older OS environments.

If you do not want to invest in Creative Cloud be advised Adobe no longer sells Creative Suite in any version, anything you find on line may have issues with registration and this event Adobe is not obliged to help you register software they no longer support (e.g you could get yourself boned if adobe shut off/decommissioned a registration server, or the person who sold you the software has it still registered to another system and never de-authenticted before they handed you the disks and you paid them so you have installer that won't authenticate the serial # you were given because it's in use)

you may wish to review Affinity Designer as a far less expensive) alternate or GIMP as a free alternative.

https://affinity.serif.com/en-us/

https://www.gimp.org/macintosh/

If you want to stay in El Capitan, you have three choices.

1) Purchase Snow Leopard Server from Apple. It's no longer available on Apple's site, so call and ask to purchase a copy. It was last selling for $20. Then purchase either Parallels, VMware, or use the free VirtualBox. Install any of these three virtual machine managers first, then Snow Leopard Server as a host OS within it. Once that's done, you can install Photoshop CS in the VM and run it from there. Total cost using the free VM option, $20 and your time to install everything and set it up. Tip: All VM's default to a very small video resolution of 1024x768. To increase it, assign more RAM in the VM's preferences as virtual video RAM.

2) As JimmyCMPIT noted, you can no longer purchase CS6 online. But as the link notes, you can still get it by calling Adobe directly and asking for it. This will last for as long as Adobe has copies left to sell. It won't be cheap. CS is much too old to be eligible for any kind of upgrade price.

3) Also noted by Jimmy, there are much less expensive alternatives to Photoshop that may suit your needs. GIMP as noted is free. Most of the others are under $100 and can be downloaded as a trial version.

http://pondini.org/TM/14.html

see this article

Use Time Machine to back up or restore your Mac - Apple Support

undertand OS X went through major changes from when you bought CS1, part of that was the entire system architecture changed from PPC CPU's to Intel CPU's which opened the door to a lot of developers who could write windows software had a closer relation to what could be now done on the mac as a result (as Esquare mentioned) PPC aps don't run in newer versions of OS X, Apple killed it, and Adobe doesn't want you buying old software when they can bang you out for a monthly charge for photographers needs it can be $9 a month. while it not great and I hate the idea of "renting" software it's got a 30 day trial

http://www.adobe.com/creativecloud/photography/elements-switch.html?sdid=KKUCC&m v=search&s_kwcid=AL!3085!3!93731941218!b…

the other Adobe alternative (for now before they phase it out I suppose) is Photoshop Elements 14

https://www.adobe.com/cfusion/store/handlers/elicensing/trialconversion.cfm?prod uctId=057&platform=Windows&locale=en_US&…

for $99 and you own it, but that's not a guarantee is will work as Apple builds new updates or new OS's and you upgrade.

Personally I'd look at the alternatives. GIMP has a big following with 3D artists and game modders so their is a community of users and Affinity appears to be give Creative Cloud a run for it's cost in terms of design and ability but I don't know how big the user base is. Having a user base is good because there are free resources on things like YouTube that can get you acclimated and their are users groups when you are looking for something specific.

Once you have restored your Mac to presumably Snow Leopard, you can then partition your hard drive, if there is enough available space remaining (30-60Gb) or add an external hard drive and install El Capitan there. You can then use the "dual-boot" method (Option-Restart) to determine which flavor of OS X to boot into and run and have the best of both worlds, just not simultaneously.

To have them simultaneously, as mentioned before, you would have to install Snow Leopard Server ($20 available from the Apple Store by telephone only; ask for part #: MC588Z/A; be insistent - it is available) into a virtualization program such as Parallels:

[click on image to enlarge]

Installing Snow Leopard Server into Parallels for DUMMIES:

http://forums.macrumors.com/threads/installing-snow-leopard-and-rosetta-into-par allels-7-in-lion.1365439/page-23#post-17285039

Affinity Designer and Affinity Photo are consecutive Apple Design award winners, that have free trial software, and are available for under $50USD each in the OS X App Store. Not subscription-ware, support forum, and accommodate Photoshop (not all) plug-ins. They are giving Photoshop and Illustrator a run for their money. I own both. I have used GIMP, but these really are professionally designed tools and I haven't used GIMP in a long while.

I posted the wrong image:

Here is Adobe Photoshop CS running in Snow Leopard Server installed into Parallels for use in Lion, Mt. Lion, Mavericks, Yosemite and El Capitan:

[click on image to enlarge]