How do you install a spoiler?

I want to buy a spoiler w/ led brake lights onto my car and dont have enough money to pay someone to do it. i'm not very knowledgeable about cars at all. can someone please give me directions on how to install or how much it would cost to get it done? i have a '95 2dr integra btw. someone's willing to sell their OEM spoiler from their '95 integ for $40. good deal?

btw, i'm in the bay area

Yes $40 for an OEM spolier is a good deal if it is on good condition. What you need to do is get a large piece of cardboard and make a template of the bolt holes then use the cardboard template to mark the hole on the hatch. I would use some masking tape and tape the cardboard to the car and walk all the way around an make sure it looks straight. Also you will need to drill one large hole on the right side for the wires. Also there are two small dots on the under side of the lip on the hatch, those are where the 4 bolts holes that hold the spoiler on should end up.