when you hit lvl70, all the end game dungeons is 10 and 25 man, without a guild, you wont be able to run them

everytime u see a player questing near you, ask to join him...then if he is friendly and u get along, keep him in friends list....then ask if his guild is accepting applicants

you need to build up a minimum of 4-5 regular quest buddies....a tank, healer and dpsers....so you can run 5 man dungeons togther