I can't get my [hp psc 1210xi all-in-one printer, scanner, copier ]to work!?

Actually to tell you the truth I do have it installed but the thing is that I can't get the scanner part to work. I try to scan somethin and it come up on my computer screen but it never does! I don't even know what program to use to get the paper in the scanner to show up! ANY HELP!!!!???!!!!