ZBrushCentral

Need some help combining and making sub tools

im am some what new to zbrush and just recently have learned alot im trying to make a model then 3d print its an d so far it going well ive been watching the 3d printing tutorial on the zbrush tutorial page and im doing everything hes doing. i mad the body with legs and arms attached made the head separate and made the hands separate just like he did. but at one point he said he combined the head and neck with re-topology. and thats where he lost me.

ive been doing as mush research as possible read how to do retopology did that tutorial but i cant seem to figure out how to combine the arms and hands and the head and neck. also in the video he separates the head-neck piece from the shoulders and he separated the arms from the body idk how to do that.

i need like step by step help or may be a video that some one has made.
P.S. i tried using subtool master as well to combine them but that doesnt seem to be a very good joining