Hi Sarah;
There doesn't appear to be much available as far as repair manuals specifically for your truck. I just bought a very good re-print of the factory service manual for my GMC from "Faxon Auto Literature",so my first shot would be to contact them and inquire what they have that applies to your truck. Also,a search on eBay should bring up at least one of every book or manual in print for it.
Next-ask lots of questions here on the forums. We've all been where you are,so no question is too stupid or silly. These people all love old trucks and are happy to share their considerable experience and knowledge,especially with someone who really wants to learn their truck.
Another good thing will be to get a few parts catalogs from places that specialize in old Chevy trucks,like Golden State Truck Parts,Jim Palmer,Truck shop,there's several others you'll see mentioned here. With these,you not only can find any parts you might need,but as you browse through the books,you can see what many parts of your truck look like without rust and grease on 'em;it sometimes helps you identify parts you might need to service on your truck,and sometimes by looking at a new part you can see where it's bolted or how it's attached to your truck. (Plus-you can't own an old truck unless you have at least one parts book with everything that'll fit your truck circled! It's the law!

) And remember-this is FUN!!
Speed