That PC uses a conventional mini tower case with a bottom mount PSU, so upgrading it should not be hard. They sold several versions of that model, so list what specs yours has.
CPU, GPU, PSU, etc. I believe the first thing you'll want to do is replace the PSU, but I won't know until I have an idea of what it came with. If you can post a picture of the inside with the side panel removed, all the better.
Btw, I know I'm old, but I had to look up ELI5...lol.