Though most families have moved from the old school garage mechanisms to electric garage door openers, there are still some people who, for whatever reason, don't want to use an electric garage door opener. It makes sense if you live in a particularly crime-vulnerable area- manual garage doors tend to be more secure. You can lock them with a padlock, and no one can get their hands on a spare opener and get into your home that way.
Also manual garage doors have the advantage of being more cost effective and easier to install and repair. As is true with any complicated piece of electronics, electric garage door openers simply have more parts and therefore can be more trouble. Most people think they payoff is worth it, but there are a few holdouts!
If you want to do a manual garage door installation, all you need is a good drill, a hex wrench, and open-end wrench, an afternoon, and a lot of confidence with mechanical parts. You also need to be completely comfortable with the idea that torsion springs hold a lot of pressure and are very capable of causing severe damage.
The basic steps, to give you a general idea of how it's done, are as follows:
Step 1: Arrange the bracket and the horizontal angle, and screw/bolt them into the jamb.
Step 2: Hook up the torsion tubs and the springs. Put both into each bracket on each side.
Step 3: Measure the length of the unwound spring, the 'release', and then put each spring in each bracket.
Step 4: Bolt/screw down each drum, one at a time.
Step 5: Attach the tub retainer.
Step 6: Wind the spring.
It's the last step that's the most dangerous! If you're not sure, don't be afraid to call in help for a professional garage door installation. It's still cheaper than paying for an electric garage door.