I worked for over head door for a few years. Residential doors aren't that hard to install.
Dress all the panels with the correct hinges first. put the rollers in the hinges. Most of the time depending on manufacturer the hinges are numbered. shortest hinge on the bottom, tallest hing on the top usually the top hinge has an adjustment.
Attach the cables to the ground panel and center the panel in the opening. THEN, put the track up. Only attach with a couple of lags so you can still adjust. You want around an inch of play between the rollers and the doors.
after the bottom panel is in place, and the two uprights are in start putting the rest of the panels in. Leave the top panel out until last.
Install the horizontals and radius'. You want the track to line up perfectly whilethe horizontal is level. It's easiest to have someone hold the back of the horizontal level while you line up the where the track sections meet in the front.
for torsion spring setups sometimes the bearing plates will be seperate from the horizontals, sometimes the bearing plates will bolted to them.
With the horizontals in place you can install the top panel Then run all the cables behind the rollers to the top.
Then install your springs and cable drums. Two different ways to do this. You can put the spring(s) and drums on the shaft first, or sometimes you can put the spring on the shaft after you have the shaft through one of the bearing plates. Just make sure that the spring is going the right direction. other wise when you tension the spring it could unwind off the cones. I find it easier to have the spring/drum/shaft assembly together on the ground, then walk it up the ladder and install. Mark the center line between bearings So that your shaft assembly is level and straight. for a single spring It'll probably be offset so that one side doesn't go faster than the other, for double springs, the middle bearing plate will be in the center of the door.
After you get the springs up, make sure to put some vice grips over a few of the rollers to keep the door from going up. Wind the springs.... Carefully, with the right kind of bars, in the right direction. after the right amount of turns tighten the set screws run the cables up into the drums, twist the drums so there's slight tension on the cables, as equal on both sides as possible and tighten the set screws. Make sure the drums are on the right side, sometimes they're labled, sometimes not. After the springs are tensioned, the cables are installed run the door up so you have about 1 1/2 panels in the air, then re vice grip everything. Now you can adjust the horizontals and install your rear drops. Then it's just a matter of making everything straight, square, level and ensuring the proper gaps for your rollers. Making sure that nothing rubs.
If you know who made the doors, you could probably call a local door company, tell them the size and dimensions, tell them the rough size of the spring, the model/series of door and they'll tell you the amount of windings. Normally for insulated ( not wood) 9x8 residential doors with no glass, you're probably looking around 7-8 turns.
extension springs can be a little harder, and nowadays are usually with non insulated doors. with those you need to have the doors all the way up before they're installed.
Hopefully I steered ya in the right direction if you chose to diy.