The core book is pretty dense collection of rules to try to learn from without some experienced help. If you and your friends have never played any pen/paper RPGs before, I would suggest picking up the Beginner Box. That does an excellent job of teaching those dense rules, as well as the basics of roleplaying, gamemastering (running the game for other players,) character building, leveling up, and a lot of other concepts that many more experienced gamers will forget to talk about in an advice forum. The PDF is only 9.95, or see if you can pick up a physical copy at your FLGS (friendly local game store.) There are a bunch of free download add-ons once you have played through the contents of the box.
Also, you can contact your closest Pathfinder Society Organized Play regional coordinator for advice about how to find, or start games in your area. Organized play, while not the only or necessarily best option for play, is a good starting place to learn the rules and meet other more experienced gamers. It also strips out some of the more complicated and world-inappropriate material that might overwhelm new players.