indelible_mark wrote:
Can I go to OS10.13 in one step?
In theory yes. Once in a while a particular Mac may first need to have macOS 10.11 installed probably to make sure the system firmware is at a specific level.
Can I use these discussions pages to find people to help me, or do I have to find someone on my own?
No. Apple does not allow users to post any personal information. Besides I would not trust complete strangers. Who knows what junk may be on their computers that may contaminate your Mac. If you don't know anyone with a compatible Mac, then maybe you can try asking at your local Apple Store or Apple Authorized Service Provider. For a small fee they may assist you in creating a bootable macOS USB installer.
Does the helper have to have OS 10.11 installed, or just have the install application in their folder to create a bootable USB start up? In other words, can they be running a more recent OS, but be a 2008/2009 model(?) which seems necessary to create the bootable USB?
No, the other Mac can have any OS installed as long as the laptop could be running macOS 10.11 or 10.13 (i.e. the Mac is compatible with macOS 10.11 or 10.13). In my previous post I listed the general model years compatible with each OS. All the other Mac needs to do is to download the macOS installer to the Applications folder and if the installer tries to install, then just quit the installer so you can use the instructions in the Apple article to create the bootable macOS USB installer. If you are downloading the macOS 10.11 installer it is accessed from outside the App Store and will download as a .dmg file. Follow the instructions in the Apple article to extract the downloaded "installer" to the Applications folder so that you can create a bootable macOS USB installer. None of these options will hurt the other Mac in any way especially if the other Mac is running a later version of macOS. If the other Mac is not currently running the OS you are downloading, then the installer may run and automatically reboot the Mac to upgrade it so you must pay attention to quit the installer once the download has finished.
Here is the Apple article with the instructions (pay close attention if downloading macOS 10.11):
How to create a bootable installer for macOS - Apple Support
You can use the information in this article to identify exact Macs which are compatible with macOS 10.11 and 10.13 since the information I posted earlier about the years is just a general guideline since a few compatible models may exist outside of the range I listed since I was being cautious.
https://eshop.macsales.com/guides/Mac_OS_X_Compatibility
