HI AND WELCOME TO THE SITE AND DIGITAL SCRAPBOOKING!
After you have your initial canvas open... open your photo in PSE and then make sure the move tool is selected (this looks like 4 arrows at the left by default).
Click on your image and then while holding the mouse drag it and drop it into your preset 12x12 page.
If you want to resize your photo you can then again make sure you have the move tool selected and hold the shift key and then mouse over the image on the "node/square" indicator and pull it in our out to the size you want it to be. Press Enter.
For this step above and below - to quickly start out the same way - "control T"
Same thing if you want to rotate it... but this time mouse over the node/square until you find the "turn arrow/curved arrow" this will tell you that it's going to rotate it opposed to resizing it and NO NEED to hold the shift key for this step.
Some other links of interest:
How to crop photos
http://scrapbook-bytes.com/cgi-scrip...icle_144.shtml
Setting up your first page
http://scrapbook-bytes.com/cgi-scrip...icle_171.shtml
Using Brushes
http://scrapbook-bytes.com/cgi-scrip...icle_145.shtml