First I uploaded the original to Pixlr-o-matic (PS Love that site! Plus it's an iphone ap as well.)
Then I opened the picture in Photoshop. I added the text in the French Script MT font in white and added a drop shadow layer effect. I also made painted in a grey cloud behind the text of his likes and set it to 50% opacity. This helps the text stand out from the background a bit more.
Not too hard at all. Pixlr-o-matic really did most of the work and I just had to add some text.
Wouldn't it be fun to have a whole book of these collected from his first 10 years or so? Or even up through graduation?