how do i figure out which keywords i should be using? i have several hundred listed
I am assuming you have access to a computer; first you should power on and login an operating system that has a web browser and access to the internt, open a web browser and then access a search engine, for example by typing "http://www.google.com" in its address bar, then you should perform a search (e.g. "adwords how to target keywords" but without the quote), if you are using google and do not have instant search enabled you can click on "I'm feeling lucky".
Then, you can read through the search result's websites after what you will be able to apply some of the stuff you learned or ask smarter questions.