Dear Ambassdor of Mongolia

Im Yemen (arab country) nationality.i would like to visit Mongolia.And in my country we dont have embassy of Mongolia.So im thinking i can get Mongolian visa from China.i want to visit and stay in Mongolia for long time.i have friend in Mongolian.can u tell me how can i get mongolian visa? and can stay longtime there?
which papers i have to apply? send to me reply by my email.
thanks a lot
Mohammed