What he did was adjust the forward lean of ur binders. Most likely he did this because a)you were not bending your knees enough or b) you were not getting enough power on your heelside turns. Forward lean is usually helpful when turning, but if you end up doing any boxes or rails, you are going to want to reset the lean back to zero.
As for binding angles, whatever feels comfortable to you is best. Start with something around 15/-6 and then tweak it from there, unless you are riding switch a lot, in which case try something more along the lines of 15/-15.