Get your feet wet using any of the free fantasy league offers that yahoo or nfl.com provide (etc.etc. there are a handful of others).
Stick to a relatively small league size. A larger one can be overwhelming...especially if you're new to professional football to begin with (just on the outside chance).
Feel free to grab a fantasy football magazine or two that hits the shelves a month or so prior to the first week of the season. They generally tailor their info to new players and may not have the most intricate and concise opinions, but overall will prep you well.
Do vague searches on the internet for fantasy football material. There are grips of pages with tons of material hand over fist.
And always come back to the cafe if you have any questions. Just stay away from "Duke". He's a real prick.
Only 3 leagues this year. No sense in rooting for everyone in the NFL.