This is a pictorial guide like the ID purchase page. It is mostly self explanatory.

What is a championship?

A championship is a special lobby that allows games to be played in a set period of time, in which players are ranked on their performance to give an overall ranking. It functions more or less identically to a regular lobby, except that you have to be invited (someone sends you the link to it) to play (unless you organised it, of course). Players' ranks are determined by the sum of their best 3 or 5 successive game scores.

Setting up a championship lobby

1. To make a championship, follow this link (Tools) on the Tenhou main page.
   
2. Pick "create lobby".
   
   
3. Choose a championship lobby.
   
   
4. You will be given two links, the top one is the link you give to other players, and the bottom is the administation page to set up the championship rules and such. Below is a key to the administation page.
   

That's all there is to it.