If you have TD try the Quick Tour and Help in the Help section. You can pretty much get what you need there is you are the type that can learn through manuals. Other than that I would not personally recomend the Mercury Training. Maybe try the "training" tab above on this website? I haven't tryed the web based stuff, but it's likely cheaper than Mer.
I haven't seen any free training floating around. We produced our own training because we produced our own workflows etc around using the tool and found that users are better off if the training is tailored to the environment etc.