MTGTemple has 4 levels of tournaments.

The first level is impromtu tourneys or minis. These are
ran at judges discretion throughout the day. This is the
only level of tournaments without prizes other then rating.

Next up is Temple Challenges (TCs). These are scheduled daily
at varying times and formats. TCs are Single Elimination and
have prizes. The winner of a TC gets 1 bye to the Temple open
and 1 Token per 3 players. You can find an Explanation of Tokens
Here.

Temple Opens (TOs) are ran 1-2 times a month. TOs have varying
prize pay outs and give out store credit to the first 3 places.
You can find out more on Store credit here. The first 4 or 8 places
(depending whether its a top4 or top 8 cut)are all invited to the
Tournament of Champions.

Tounaments of Champions (ToCs) are ran Bimonthly and are invite
only. ToCs have a higher prize pay out then TOs and are always 6
rounds of swiss. To get an invited you must Top4/8 a TO, turn in 200
Tokens, win a contest, qualify on ratings or via team. The exact
qualifications vary per ToC.