Ideally most of the information you need to run and configure your server will be in the manual If something you need isn't, work your way down the resources that follow. If it's appropriate, you can add the material to the wiki, if unsure ask.
The Manuals for the User, Administrator and Developer.
Find, report and fix bugs here http://bugs.contribs.org
You don't have to be a programmer to help or use the bug tracker. Bugs also include fixing things and making suggestions on documentation, translations and the SME Server web sites.
Refer to Bugzilla Help for helping with bug fixing and verification.
There is an enormous amount of information here, a search can often find just the answer you are after. You can also find outdated, misinformed or wrong information.
The aim should be to transfer valuable information into the Manual or a Howto (with a link in the Howto List)
If you can't find the information you are after then post to the forum. If applicable, please document your answer in the wiki so it becomes a definitive answer and not just another hit on a search.
HowTo's are documents to solve a particular problem There is a list of HowTos here
Frequently Asked Questions
The Frequently Asked Questions page is to be used to document problems that cannot or will not be fixed through development of SME7. If a problem is fixed it should be moved into the Manual or a Howto.
There are a number of lists available to join at http://lists.contribs.org/mailman/listinfo
List descriptions and email archives are available here.