A couple of my buds are going to make an independent film and they have put me in charge of making the score. I am going to write the music myself and record it and all that. They came to me the other day and told me that they were going to burn the finished movie on dvds and they said they would really like the audio and sound in dolby digital 5.1 so it can be played on a 5.1 surround system and all that (i guess they are gonig for as professional as possible). I was wondering how i go about recording and mixing so the final product will be in dolby digital and all that. I am completely new to this topic so any information would help thanks

as long as your DAW can do 5.1 (DP4, Nuendo, PT HD), all you need to get is A.Pack to encode the audio to an AC3 stream. It comes bundled with DVD Studio Pro... if your friends have it, you're set.

well they don't have much software they only have iMovie so i think i need alot of stuff and i'm a beginner at all this audio stuff so im not quite sure on all the terminology so if you could maybe revise your reply to stupid person terms that would be great.

tranlation ; you need a program that is capable of recording 5.i such as Digital Performer, Logic 6 ,Nuendo to do the job

You cannot do 5.1 with what you have. What you can do is to give them the music and let them mix the final sound. Even at this you will be wanting as you need to lock your music up to the score, to do this you need an audio ap. that imports refrence movies. Depending upon what kind of movie it is the score has to be tightly intergrated into the movie. You will need a pro audio interface, and all the mics monitors ect. it take to make a studio even to do 2 tracks.
VERY IMPORTENT;you need to record at 48khz not 44.1 Dolby needs 48khz to encode with. YOU MUST limmit your music so it dose not clip Dolby dose not handly clipping well.
I have a surround studio, I have DP4 with a MOTU 2408, a suround sound amp and monitors all the way around. You want all your monitors to be the same near field monitors. I have FCP4 and DVD Pro 3 so I can mix, DVD Pro has A-pack wich is a Dolby encoder. To do this project half right be prepared to read thousands of pages of manuals and still hit walls, spend untold thousands of bucks and a massive amount of time.
Where you are at it may be best to wright the music while veiwing the movie and go into a studio to record. Sorry I can not tell you a easy way and cheap way to do this.