Heater Core Replacement, please help!

Well it has gotten to the point where it is cold enough for me to want some heat in my car. I bought the car knowing the previous owner had bypassed it and I knew all along I would have to do it , but anyway I dont have a clue how. I have the new core and Ive heard a feew suggestions on putting it in im just wondering if anyone has some solid instructions, ill take all I can get, i know its going to be quite a job but right now I cant afford to have it done somewhere else. Ill probably just have my dad help me or get a friend and see what we can get done in a saturday, but just fill me in on anything I should be aware of! Thanks
Dan
p.s. 1988 GT stock if that matters