I JUST discovered this. I keep learning and learning this program.
It does your stitching AUTOMATICALLY for you.
Scan your 12 x 12 LO.
Scan the left side.
Scan the right side.
Save as jpegs.
Open your Photoshop CS.
Open both left and right LO jpegs.
Click on File.
Scroll down to Automate.
Click Automate.
Click Photomerge.

IT AUTOMATICALLY merges your photos together for you. IT is SOO easy!!
Plus, You don't get the little shadow line in the middle of the LO, as you do if you manually stitch it.

Once this is done, Save it as a jpeg.
You end up with a rather large file.
You will have to reduce the jpg, to get it to a smaller size to use on scrapbook.com or any other gallery.

HERE is a link to what the results look like in my gallery: