What does it mean when my 6 month old computer already needs more memory?

[Madison 3:16 Anderson Rhodes]

I've had computers since the green screen..attached keyboard kind. I have never had this issue, especially so soon into purchasing a computer.

I got a computer 6 months ago for schooling and I spent hours trying to figure out which computer is best. It wasn't cheap, but it wasn't expensive either. The reviews were great..

It's a desktop. It shuts down and restarts whenever it damn well wants to, when I have ONE window open it says that I need to close it and re-open it...that my memory is low. I can NOT have 2 windows open, and google chrome no longer works even for 4 min.

I put over 100 pictures from a wrestling event, downloaded iTunes, and ever since that's when I find the issues. BUT I deleted both of those things (pics are still on my camera), and it still says low memory.

How is this possible? I barely have ANYTHING on this computer and deleted/uninstalled a lot when we first set it up because I wanted it strictly for school. I didn't even go on social media sites or anything the first few months.

HOW do I get more memory and why is this computer doing this so soon?