There are normally two methods of fitment depending on the rack you buy. A custom rack like a Ventura (which by the way, the racks they make are actually OK, I have never had a ventura rack fail, only the bags!) it bolts straight into where the luggage hooks are on the ducktail. (The silver flip up bits of metal you hook occy straps to) Just remove the hooks and the rack mounts bolt straight into them.
If you have a Gearsack rack, then it is all about using common sense. As common sense is pretty uncommon these days, it might pay to have someone who is good with there hands to help you. Now I am not saying good with there hands as in happy ending hands! As then you would most likely end up fitting incorrectly if at all. However, if you have a mate who is a builder, plumber, sparky or such, they could probably manage it.
As a guide, the brackets they give you usually mount up under the side of the ducktail into whatever bolts you can manage to find.
Honestly it isn't that hard, just remember a few simple rules.
1. make sure you take a special note of how you pull things apart, just so you can get them back together.
2. Take your time. Rush it and you'll fuck it!
3. If you are really dumb, tag all the parts with a label and seperate them into labelled boxes/containers.
4. drugs and alcohol usually speed up the process.
5. If you have any bits left over, just hide hem.....it'll be ok....promise!
6. If the rack falls off on your first ride, you've done it wrong!
Hope all this helps!

"I hate to advocate drugs, alcohol, violence or insanity to anyone, but they've always worked for me" Hunter S. Thompson.
There are really only two questions in life. 1.Which way do i go? 2.What is the lap record?