This documentation describes one of the easiest, and most common, ways to add more pages to your forum. Simply use the forum rules option and put whatever you want on the new page! Then, insert links to this new page in certain places around the board header.

If you have used this code, then (provided you followed instructions) you would have set the state of the category in which you stored all of your extra pages to "Hidden from Forum List, access via URL if known." If you set it as "Visible" you can see these boards on the main forum page, and if you set it as "Disable" you can't get the URL for the forum rules pages (so you can link to them).

Now, if you have done that, then all will be well. Or so you think! At the bottom of every topic and forum there is a drop-down menu with links to the forums that can be seen on the main page and to hidden forums. This means that members can unwillingly access the forums that you tried to hide from them.

Now, how can you prevent this from happening? Easy! Follow these instructions (No, they are not the same as the ones above!)

After clicking the submit button, if you check the same drop-down menu again, you will find that the hidden boards are gone! Hooray!

Update: Since writing this tutorial, I have also discovered that the "hidden" category was displayed in the board navigation (at the top of the board) when viewing a rules page. Disabling the category fixes that too.

Yet another update: HelenaZF discovered something interesting; once you set a category's state to "Disable", you can't edit forum rules within it. You need to set the state to "hidden" if you want to edit the content within. More info here.