Any female channeler who is of a required level (20) may come to the Tower, find any Aes Sedai (AS), and approach them in character (IC). The AS then roleplays (RP) with you, inducts you into the clan with the mob Sheriam, and gives you the introductory tour, rules, and beginning quests.
Please note, although any FC can be clanned, not every Novice will eventually end up shawling. This process is deep and involved, and holds no guarantees.
The above is copied from our Tower System outline - from Induction to Shawling. I suggest anyone thinking of joining the Tower read it first: http://wotmod.org/viewtopic.php?f=67&t=473
. Also note though any Aes Sedai can induct, not all do so and/or they may not be immediately available for the hour or so it sometimes takes to induct.