That is old Haven't you posted that in here before? And how did you do the last one anyways? Tripod, take 4 pictures of you in different places and then layer them?
Read basic tutorials, understand basic features such as layers, opacity. Too be honest one you understand the layers, start applying mutliple images and then alter the opacity, and then just tweak.. Best way I started learning, and im far from being a Pro.
And theirs only one way your learn is by trying, no by posting saying you need help.