To much to explain and this isn't the best site to get much info for a begginer. Head to the taxidermy site, and ask away. http://www.taxidermy.net/forum/index.php#3
Best place to start is going to be on deer. Either go to a school, get some training videos like rick carters mounting whitetail A to Z, or best of all get some one on one trainging with a good taxidermist as well as join your states taxidermy association. Good luck. I'm t3_Kyle on that site if ya need some info.