To your first question, Microsoft Paint doesn't have a crop function. You can select an area of the picture, copy it, and paste it into a new image file, but it's a pain. You ought to download Gimp. It's free and allows you to do almost anything.
To your second question, I'd have to know a lot more before I could help you.
just go to drpic.com and you can upload and crop it for free. Just right click to save to your pics.
because you're useless!
Resolution - go to your blank desktop, right click, go to Properties, then the Settings tab. Resolution should be there somewhere.
I'm on an old OS (Win2000) so this may have changed a bit since then.
Good answer david:)