I've gone through the various help topics, and spent a few hours poking around my device, but I have yet to find a way to forward my text messages to Verizon to report Spam (I mean, I'd really love a Carribean Cruise, but . . . ).
Long-press the text message to select it (you should see 'selected' in the notification bar). Press the envelope icon and enter 7726 (for SPAM), then press SEND.
I don't get an envelope icon, only a trash can. Pressing the menu button does not get me anything, either. My choices are Select All, and Unselect All, and the only icon is a trash can. No way to forward a text message on my Motorola Razr Maxx.
If you press a text string, you'll just see a trash can; is that maybe what you're doing? If you long-press on an individual text message, you should see the envelope icon, i.e..