If you're talking about taking a picture from one window and putting it on top of a picture in another window, all you need to do is hold Ctrl+Shift and then click and drag the photo onto the other photo's window. Photoshop will automatically center them up, Don't hold shift and you can center it yourself.
To resize an image on screen, you just do a ctl+T and then use the anchor points to resize the image. To keep the image in scale, hold shift while resizing. If this doesn' t help you, I'm sorry, but you're being really vague.
Well, all I did was copy paste... I think you are making this harder than it is. I took the Fullmetal Alchemist picture, cut him out, and then pasted him onto some flames that I googled. Then I did some fancy-ish text. Thats all.
Well, to cut-out your front picture, you should use a lasso tool. Then once you have your area selected, delete your background so that you can see the image behind. Then add your text, etc and save... Its really not much more indepth than that.