Hi mate, these training sessions are pretty open, as I understand it, just go along. If nothing else, you can watch and pick up a few basics.
But the most important thing is to learn some really basic techniques, and get out there and learn them. Get your roll together, (Learn it on concrete straight out, it's harder than it looks, but grass will give you crap technique!) climb small walls, and above all, DON'T go jumping off crap, until you know what you're doing, you'll just wreck your leg joints.
But talking to other traceurs for tips and training in a group is probably the best way to learn, to start with. The more you train, the better, either way.

BTW, I'm 23, I've trained for a bit over 3 years, and I'm self taught. Classes are good, but not essential.