i used 2 do a bit when i was a younger n i know what u want the maths for but i forgot it all !!!
try this for set up:-
http://www.astronomy.net/articles/4/polaralign.html
u also need 2 know how find the north star. assuming u dont, find the big dipper. the last 2 stars that form one half of the bowled end of the dipper point 2 the north star. the north star is also on the handle end of the little dipper.
your probably best off just getting a begginers book and sitting down n reading it all.
you have chosen a good time to start though. now its getting cooler at night, when the sky is clear, u get less distortion than in summer nights.
what magnification do u have ?