The alliance line get shifted automatically every 3 hours (depending on how well your side is doing in AB at the time). When it does, if you have enough faction, you will automatically get a town.
u may have millions of faction, but if u dont have more faction than other alliances, then u will not get a town. Also, if ur a sub-guild in an alliance that owns a town, only the lead guilds name will be on the town.