I would forget about the on-board LCD for the time being and get some experience using one wired in parallel (which is well documented). When you have that knowledge under your belt then think about tackling the on-board one.

PICs offer so many functions and possibilities It is tempting to try to take on to much at once. If you do, you are likely to be frustrated and spend a lot of time getting nowhere. However, take everything one step at a time and you will progress rapidly.

Best of luck,