Windows comes with software to do that -- it's called PAINT -- and it's in your Programs/Accessories/ =========================================== If you want to do fancy stuff -- well you can download Trial copies of Paint Shop Pro -- or Photoshop ! Those are the 2 main Paint Programs. Difference in them is simple -- the more you pay the more sophisticated you get and the harder it is to learn of course ! So unless you are a future Graphic Artist in the making , Paint Shop Pro is more then you need. That's all I have used to make that avatar below my signature.
yeh go for one of them but not paint as its a bit crap.... very,very cheap paint is , but try some of the other programs sugested by jeanc1, there good.