how do i install the mach 460?

i know everyone is gonna bash me but forgive me. i purchased the mach 460 off ebay real cheap to fill in my bare 00' gt. someone gutted the system in my car before i bought the car. so, i plan on using the mach i got from ebay along with better 6x8s (4 pioneers 240 watt each) as my component system. later ill get me subs. so, basically, i ask whoever has sucessfully installed a mach 460 for pointers cuz right now, my dad, my neighbor, and i have tried but have failed to install the system. my gt already had the door tweeters with the housing so wut i purchased wus the following: tweeters for the back, 6x8s (pioneers) for the front and back, a speaker box, and two amps for the back. i have the stock deck so i think that the amp is still back there. except for the four 6x8 pioneers, this is the stock stytem. anyways, wut is the best way to install this system if i cant do it myself? dealer? best buy? wut should i do thats the best deal? n e of u who have done it thik its possible for a newbie like me to manage it? maybe there are sites offering directions, i dunno. help me out my brother stangs.