Swapping a garage door is not a one-person Saturday project, and I'll say that plainly. The sections are heavy, the torsion spring stores enough energy to break a hand or worse if you don't know how to wind it, and getting the track plumb on both sides is the difference between a door that runs quiet for twenty years and one that binds in six months. If your opener bracket and header framing are original to a 1999 build, they're often sized for the old door's weight, not whatever heavier insulated door you might want to put in - that framing check isn't optional.
What you can reasonably do yourself: clear the garage, pull old paint cans and shelving off the walls near the track, and have the opening measured before anyone shows up with a truck. That saves time on the job and doesn't require touching a spring.