I need to know more about communes?

i'm thinking about leaving home indefinitely (i'm eighteen, don't worry) and i think i'd like to live on a commune somewhere. anywhere. just to get my head straight for a while. i need to know, what exactly are most communes like? do they even exist the way i envision them? how do i apply to live on one? anyone who has any info on this topic or anything similar where a young guy with no cash can stay for a while could help me out.