Celeste, you can resize, crop etc pics in a free photo-manipulation program called "Gimp"
http://www.gimp.org/downloads/
There are tutorials available on using the program too:
http://www.gimp.org/tutorials/
Basically, for forum use, you don't want your pic wider than 600 pixels (72 dpi resolution for on-screen) I tend to make my pics 500x500 pixels for forum posting (hrm, I'm thinking I should make up a tutorial for this...) Hope that helps