Updating macOS to a newer version

High Sierra 10.13.6 is the last possible version for a mid 2011 iMac.

Also see the following from Identify your iMac model - Apple Support

iMac (21.5-inch, Mid 2011)

Model Identifier: iMac12,1

Part Number: MC309xx/A, MC812xx/A

Newest compatible operating system: macOS High Sierra

Apple frequently announces new products in Sept/Oct. The current 24" iMac was released in 2021 so it is a 2 year old model and it's possible that a newer version of it will be released soon. You may want to wait a short time to see if there is an announcement (only if you want the latest model, with the potential of being supported for upgrades for a longer time -- I have the current model and am very happy with it).

Regarding trade information , the following may help: Apple Trade In - Apple

You can also download the latest version of iTunes 12.8 (for High Sierra) from the Apple site.

iTunes - Apple

With this version of iTunes, you can import music from your own CDs, buy downloadable music from the iTunes Store, and/or subscribe to Apple Music.

Jen8219 wrote:

So does that mean I can no longer get updates and need a new computer. I am sorry, I am not very computer savvy. I do thank you for reaching out.

It means that you can no longer get updates to macOS – or to the Safari browser, since Apple bundles Safari updates with macOS updates.

You can still get some software that might prolong the usable life of the machine. E.g.,

• The Firefox Web browser. As of a few weeks ago, an ESR (Extended Service Release) version ran on High Sierra, and was still receiving updates.
• LibreOffice – a free Open Source office suite. New versions are no longer being released for High Sierra. However, you can still download LibreOffice 7.4.7 from the archive.
• GIMP (GNU Image Manipulation Program). This photo editor is complex, but has fairly advanced features; therefore, might make a good complement to Apple Photos. You can no longer get Photoshop, Lightroom, Photoshop Elements, or Affinity Photo V1 for High Sierra, but for the moment, you can still get GIMP.

I believe the commercial backup utilities Carbon Copy Cloner V5 and SuperDuper! will also run on High Sierra. (You should definitely be doing some sort of backup, whether using Time Machine, or using one of them.)

That's correct -- it can't be upgraded beyond High Sierra 10.13.6 and you cannot upgrade to 10.14 or later. If you need to install any software that requires 10.14 or later there isn't a way to do that.

Also, there are potential security issues with using Safari with High Sierra. For security reasons you should consider using a 3rd party internet browser that supports their current version with your older macOS. One example is Chrome. See: https://www.google.com/chrome/

What type of Mac (MacBook Air, iMac, etc) and what model year is your Mac? Both of those are available at Apple menu > About This Mac.