A great way to stitch photos together is by using the built in PS automated actions. In the File menu go to the Automate option, at the bottom of that menu is "Photomerge…" Using the dialog that opens up, open the images, preferably in the order you want them in, and click "ok", an option box opens with the photos at the top of the screen, sometimes the images will automatically line up a bit, usually you have to adjust them a bit, or you will have to manually drag them in, click ok, and you are done.