Hi LeBi! Welcome to the Windows 7 Forums website!
I was 13 once, long time ago though, LOL!
Your system hardware is a little old or outdated, but Windows 7 should run okay.
Is it asking for you to update the .NET application? It looks like that is the case from what you are saying in your post.
Have you gone to Windows Update yet and tried it? You may have to enable the "Get other updates" feature in the Update window by enabling the "Microsoft Updates" feature.
You can do this from Internet Explorer and just use BING search engine and type: Microsoft Updates. It will guide you from there.