plz help

i am really new to icon making so the basic thing i need to know is how to resize pictures to like the regular 100x100(i think thats the size). if anyone has msn..i need the icons to fit the size that they give you.im not sure if its 100x100. i have Jasc Paint Shop Photo Album 5,Starter Edition i would really appreciate it if someone could help me :)
thankyou! -stef