welcome to the planted tank!
i'm very new myself and barely got my tank planted about 20 minutes ago, haha. i'm carpeting with HC and doing it emersed ( dry start method), if it's potted then it'll come bedded in rockwool ( that cottony stuff... you'll see what i mean when you get it) , work the roots/hc loose from the rockwool gently and make sure you get most of it , if not all out.
get yourself a nice set of LOOONG tweezers, grab the HC by its roots and work it into the substrate. i found that if i work it in and pull the tweezers out, the substrate and roots will come with, so i just used a finger and held the plant down as i pulled the tweezers. these forums are plentiful and has lots of great info! goodluck on your tank!
fyi: i bought 8 pots to fill my 20 gallon, you can check out my journal and follow that if you want, i'm not too far from where you'll be soon!