The Tcl Tutor [L1 ] is a free, downloadable, multi-platform tutorial for Tcl. There are over 40 lessons, and each one shows sample code. What makes it even more useful is that the tutorial window has three panes.
The first pane shows a lesson. The second pane shows editable sample code. The third will let you run the sample code in a completely self-contained manner so you can change parts of the code, run the example, and see how your changes affected the output.
Try it!! It's a great learning tool.