I know this is a stupid question and ive searched ,but i havent found anything i know use duct tape when you cut the line ,but how do the fittings go own? Sorry for the stupid question ,but ive never done it and just would like to know thanks

 

http://www.carcraft.com/howto/2988/index5.html

This is a pretty good article on how to do it.

 

Im assuming you are just talking about a AN hose end fitting. If so, once you have cut your line, you losen the collar on the side that the hose slides into...then you have to push the hose into the end of the fitting...twisting and pushing in order to make sure you get it all the way in there. Then just tighten the collar down again.
If you were asking how to cut it...you method of duct tape is about the best. Also, dont use a hacksaw, use a die grinder with a cut off wheel, the higher rpm speed reduces freying(sp?). Or...if you really wanted to do it right, you could buy a set of braided hose shears. They are quite big and kind of expensive if you are only going to use them once. Search for them, you can find them all over. They look kind of like a big pair of bolts cutters.
Kyle

 

the giant hose cutter thing will probably give you the cleanest cut, and some prefer to use electrical tape to hold the braids together, same idea as duct tape,

 

Using a large concrete chisel also works very well to cut it.

 

Use Aeroquip hose, it doesn't fray at all so you don't have to even tape it off.