If you're new to Photoshop, the Pen Tool can make about as much sense as a ketchup-flavored popsicle. Nonetheless, it's one of the most useful tools in the entire program, and it's definitely worth taking the time to learn how to use it. This great tutorial will get you up and running.
Coming to you from Nathaniel Dodson of tutvid, this helpful video is a great introduction to how the Pen Tool works to create paths, particularly if you've shied away from trying it out yourself. The Pen Tool is perfect for making precise selections, especially when complex objects are involved, and if you're serious about your retouching, chances are you'll have to learn it as some point. The beautiful thing about it is that paths are fully editable, so if you mess something up or need to make an adjustment, it's no problem. If you're still having trouble wrapping your head around it or just want some extra practice, take a look at the Bézier Game, which offers free guided practice using the Pen Tool at increasing difficulties.
And if you'd like continue learning the basics of photography, be sure to check out "Photography 101: How to Use Your Digital Camera and Edit Photos in Photoshop!"