recovering from injury

Hi!! I have decided to undertake training for a triathlon. I developed pyriformis syndrome as I was training for a marathon this summer I had pain to the point that I could not sit or lay on the affected side. Anyway, too many miles I guess. So I thought that I could train for a tri instead. I love endurance sports and feel a little unsure as I head off into unchartered waters. I am not concerned so much with being able to run or bike, I do those well. I am uncertain about things like swimming (that will come, huh?) and knowing how to change, learning the lingo and knowing what to do and when to do it. I have already printed out some training plans and am looking into bikes. I have a klunky old mountain bike that I ride around with my kids--will be okay for now as a beginner i assume. Anyway, I am glad to have a resource in this website--I live in a very rural area and not a lot goes on out here in this regard.