Question

How do you get egg moves?

Answer 1

Breed a male with the egg move and a female of the Pokemon you want to have the egg move on. They must be in the same egg group. For example, if a male Farfetch'd with Air Slash breeds with a female Samurott, you will have an Oshawott with Air Slash. They are both in the Field egg group.

Answer 2

its simple :

there is this thing called breeding/egg groups now, a pokemon have up to 2 egg groups .
if there is a move that the pokemon can learn through breeding (mostlly known as egg move) and if the pokemon that has the move and the pokemon that is able to learn that move through breeding are from the same egg group they can breed.
the pokemon you want to have the egg move has to be the female and the pokemon that knows the move has to be the father.
when breeding these 2 male and female pokemon from the same egg group the new born will have the move .

http://pokemondb.net/mechanics/breeding

hope this helped :)