Take the bike to the local bike shop and have it tuned up. That will fix most of your issues and get you on the road, you can also get a water bottle and cage from them .
After you do that pick up
http://www.parktool.com/products/det...9&item=BBB%2D2 or
http://www.amazon.com/Zinn-Art-Mount.../dp/193138259X and study up on how to do the light stuff your self.
Your local bike shop or many online retailers carry a big selection of lubes for cahin ,forks and so on.
Good luck and enjoy your trek 820 , its a fine beginers bike .