First, Welcome to the forum! I am in the process of repairing one and mounting it on my 1984 GL1200 (
http://www.vetterowners.com/threads/vetter-rooster-fairing.203/#post-1098 ). I found that there isn't very much information out there on them.
First question: Does your fairing have the silver bar sticking out of the bottom similar to the one on the photo below? That is how it "should be attached to the handlebars with the hardware that comes with the fairing. If you do not have it, then you need to improvise.
The way I am mounting mine is I am using the mounting hardware from an old National Cycle windscreen that I had laying around that I did not like ( I am a bit of a pack rat so I don't get rid of things that often unless I can get something ($$$$) for it

). The hardware for that windscreen will also work for the Rooster at the bars and the forks.
For attaching the fairing at the front (around the headlight,) I bent some metal brackets up that came with a Rooster rectangular headlight/turn signal kit that I also bought (it was missing the turn signals so it was dirt cheap). Those instructions are attached to give you an idea of what kind of instructions came with these things.
The backwards "Z" shaped bracket is what I bent up to create an offset so I can clear the huge headlight bucket of my 1200.
Then I just attached one of the slotted bars to my bracket and that connects to the fork attach point at the Red Arrow in the picture above.
I have some fine tuning to do to it, but this is going to work. I have already had it on the bike and mocked it up and rode down the road with it on before I started painting it, so now it is just a matter of waiting on some warmer weather (again

) and then I can finish that project up.