Help with Tcl/Tk 2-D GUI

I'm starting a new job in a few days. One of my first tasks will be to modify th 2-D GUI of a package. In the following I'll have to evolve the 2-D GUI into a 3-D GUI allowing for 3-D rotations of 3-D structures. I've never used Tcl/Tk in my life so I would greatly appreciate some advice about an easy tutorial with plenty of worked out examples ... if available. I'm running SuSE 9.3 on my laptop and have zero time to replace it with SuSe 10 for the time being. Thank you in advance for your help. Maura