And if you find that they are too big, I use Pixresizer to make them the right size. Its very simple, you just click on "Apply recommended" which I think is 600x450, then save it, then upload that through Photobucket or whatever photohosting site you are using. I have used Photobucket and the Disphoto site, both are very easy once you have got the hang of it!
It is easier than it looks Totally Angelic - I found when I had done a couple (which took ages) the rest were easy, when I'd got the hang of it. If you get stuck, post here and someone will help out