The tavern is a place to meet for players, run by players. It is not a kin but a location in LotRo and a website which people from all kins are allowed to use.
The tavern will have an organized event one weekend every month. Next to that everyone can use it as long as you respect the values of Chicorya, the owner of the tavern.
If you want to organize something big, please check on the OOC forums if the tavern is not used that day for something else. When you like to organize more often or want a job in the tavern, Chicorya is willing to hire you. Again you normally don't become part of a kin then but you can get an official status on the website and additional rights on the chests and decorationmodes of the Tavern.