get used to getting your ass kicked. that part doesn't really end if you're training with a good group of people.
i tell everyone that's new to just brace themselves for a few months of getting destroyed. everything is unnatural, the moves seem complicated, you have no idea what to do in positions, you have no cardio, everyone is stronger and faster... it's frankly demoralizing.
you need to understand that everyone before you went through that.
but keep plugging away and eventually you'll notice that you're kicking the shit out of some new guys that joined a few weeks ago. then some of the people who were destroying you when you first started will need to work for it, then one day you'll catch one of them in something.
as for finishing moves, keep it basic. cross collar chokes in the gi, armbars, triangles, RNCs. the more basic the technique, the more effective it is.