Unfortunately, there is no print function in Garmin Training Center (GTC). The best you can do is use a screen capture utility (such as SnagIt, etc) or native Windows screen copy and paste into something else like Word for printing.

GTC is just...basic. If you're willing to upload your ForeRunner data to another program (such as SportTracks) or one of the web sites (such as Motionbased.com) you'll have other options for printing.