you get ascended after you beat elona's reach, thirsty river and dunes of despair. you gain 50k xp and warp to the dragon's lair. you need to ascend to be able to enter the UW or FoW.
you need to complete all the missions until you get to ammoon oasis, then run to augury rock to begin the ascension quests. from augury, you'll find a lot of people running to each of these 3 areas.
HAve to beat 3 missions in desert, Dunes, thristy rivers, elona, then you goto augury and tell him you wanna goto mesa, then you fight 1-1 with someone and if you cant kill him, take off all your attacks kills and put on dumb skills like remove hex, elemental resistance, mantra of fire, mantra of recall, etc and 1 good skill that he cannot use on you. Like if you a ranger and use bow skills, and go up to him, he uses an ax and cannot use your bow skills. Some classes he is tough, if you hate a skill he uses on you, dont use it yourself. He is a bot so he uses your skills you use better than you.