Sorry guys im new but im only 16 and i want to learn as much as i can about chevy diesels im already learning alot but want to learn more.dct codes where are they located? how do i read them?how do i take them out? ya know dont mean to sound stupid but need some help thanks!

It will help you to get the best answers if you make a signature and list the specifics about your truck. Depending on what you are driving there are several answers to your above questions. If you have a pre-1996 there is a good write up at Kennedydiesel.com under 6.5l parts/tech tips.

looking at a 94 chevy 3500 crew cab dually,6.5

In that case the info on Kennedy will work great. It's really easy to pull the codes just bring a paperclip or a short wire of some sort and a note pad with you. Also you can get the vin and take it to the dealer usually they will pull the service record for you. My dealer gave me a whole build sheet on mine.

Sorry guys im new but im only 16 and i want to learn as much as i can about chevy diesels im already learning alot but want to learn more.dct codes where are they located? how do i read them?how do i take them out? ya know dont mean to sound stupid but need some help thanks!
Welcome to the site a lot of what you seek is in welcome notes and FAQS

Turbine Doc has done some really good work setting up the FAQ section, if you want to learn a whole lot of info on these trucks set aside some time and do some serious reading on this site. In most cases if you have a question someone else has too and there will be a ton of usefull info at your fingertips.

DTC for OBI-I trucks from FAQs http://dieselplace.com/forum/showthread.php?t=16399