radio wire? 08 colorado

i have an 08 colorado with onstar, on the onstar harness there are repetition of the same wires, which one do i use? can you give me a walkthrough step by step on how to install a new headunit in detail? (the radio is an alpine cda-9830, and the truck is 08 chevy colorado

i have the radio also hooked up and its not turning on but when i directly hooked it up to the battery to check it turned on

i have it hooked up to a onstar harness, i color matched every thing and i dont know why it wont turn on, and i checked the fuse box under the hood, and i cant find a secondary fuse box,the harness has two dimmers, remote turn ons, power, and rear speakers, i had a kenwood hooked up the same way i have my alpine hooked up the other day but my alpine wont turn on

check the module for output. ign constant etc..... if thats not it i had a coworker troubleshooting an 08 silverado for an hour i walked over unplugged the module for 30 sec., plugged it back up and worked like a champ. several manufacturers work different ways. some turn the key wire off for onstar and some mute. and if its not that maybe u just have the wrong interface be sure to check the listings as they are not all the same. p.s. the ones for $35 from wal-mart suck.the best part of a job is seeing the bumper get smaller over the horizon

i'm pretty sure its the right onstar harness its an metra one that was 125 for my truck, and i had a kenwood radio hooked up this harness a few days ago and it worked fine