It is very easy almost all is done automatically by Photoshop. I am using Photoshop CC I know that Photoshop CS6 is able to do it as well.
Open Photoshop and locate Automate and Photomerge in menu:
Load all your files you want to merge. Leave Layout option set on Automatic. If you do no like result of merging try to choose some other option Perspective or something else:
Now save your image and that is it.
Any questions feel free to ask in discussion bellow.