Sounds like mobo explained it pretty well.
I would add though that the arrow wants to sit on the prongs,not inside them if I am making this clear,hopefully.The prongs are adjustable to open up and close to accomodate different diameter shafts,have it so that maybe an 1/8 of the shafts diameter is in the prong.
You also want to have the arrow on the prong and try to level it with the berger holes,thats the mounting holes where the screws connect the rest.
Another important aspect is to have it centered of the riser and string.This is called centershot.If you dont have the proper tools for this job and want to get it as close as possible then nock an arrow,have it sitting level with the mounting holes,hold the bow as though you are going to shoot it.Now,line the arrow up with the string and adjust the rest to center as close as possible.This will get you in the ball park and make tuning and sighting in much easier.
Better yet,take your bow to a shop and for real cheap have the pro do it,explaining what he is doing along the way,get involved with the setup as much as possible and you will be shooting good groups in no time.
Oh--the odd colored vane(fletching) is the cock vane,it will point down.