It is listed under "Getting Started" on the home page. You could put it in 19 different places and probably less than 1% would even read it.
When you click "Hide A Cache" it tells you this:
Before submitting your cache, please familiarize yourself with the informational articles contained in the Geocaching Wiki (see link above). These articles establish the rules and guidelines for hiding caches, selecting containers, etc. Once your cache has been hidden and submitted by you, it must be approved by the OC Team. Once approved, it will be available on this site. Remember that your geocache is your calling card, and others will evaluate it in the logs of your cache and via the rating system.