Icons That Switch From One Pic To Another..

Hello, I have a question on how-tos.

I was wondering how do you make and icon that goes from one pic to another?

I.E. It shows a pic of a girl then flashes over to a boy.

Please, if anyone could help me out on that.. I have PSP 8.0 and to admit, I don't know if my program supports what I want to learn; but if does, can anyone please help me out?

Thanks in advance. :D