There is just so much stuff in the pack that it would take weeks for anyone to teach you everything.
I would encourage you to start on a single player world and start out slow. Do the stuff you know then proceed with babysteps.
Read the most vital parts you need to know on the wikis and leave the rest for later. Taking in everything can be mind-crushing and usually gets you lost and confused.
Watch some Direwolf20 videos on youtube on any particular mod where he gives a proper tutorial how the things with the stuff works.
Welcome to FTB, the adventure with the virtual blocks will begin here!
And might be the end of your social life