GIMP is totally safe to download.
If you typed in paint.net, that's not correct, that's a site for actual paint (for walls and stuff) you need to go to
getpaint.net.Both are
totally free to download, and both are
totally safe from bad crap. They are really good if you want to do in-depth art/drawings that could be outstanding. Also, it is really fast to download both, but if you have a slow, or a not-much-memory-left computer, then it's best that you don't get them.
(I can only assume you are under 13) If any of your parents don't allow downloads, then tell them that both are safe, free to use, and very good for making art.
www.getpaint.net/www.gimp.org/Also, what kind of computer do you have? Mac or PC? If it's a PC, then what kind? (Windows, Linux etc.) If it's Windows, then what version? (Windows XP, Vista, 7, 8?)