yea, basically if u want to sell items u can sell them or buy items u can buy them
f2p are capped at 250,000 credits so some things on there u can;t really buy
there is a gtn section in the republic fleet and the imperial fleet
also in the capital worlds curounts and dourrmad kass(i don't how to spell those)
on courrounts its near the senate palace and there are stairs that lead downwards