A new garage door install is not a weekend job, and we'll say that plainly. The door itself is heavy, the torsion spring is under enough tension to break a hand or worse if it lets go while you're working on it, and getting the tracks plumb on a 1969-era opening that's shifted out of square over fifty-some years takes more than a level and a good guess.
Where a homeowner can genuinely help: clearing the garage, pulling the old door opener's remotes and chargers out of the way, and knowing in advance whether you want insulated or standard, because that decision affects the order lead time more than almost anything else.
Our honest limitation here: we don't do the electrical work if your garage needs a new circuit or outlet, and we don't frame carpentry if the jamb needs to be rebuilt rather than shimmed. Those get handed off to an electrician or contractor, and we'll say so before we start rather than halfway through.