For information on joining the forum, see: Forum - Joining.
Mark up: Apparently, at the forum, you can use HTML markup and also LaTex. You can also edit your posts if you click on the “gear” symbol.
To effectively use the search box on the forum, you need to understand the quirks of the search string format. See this discussion.
Note that this applies only to searching on the forum, not on the wiki.
TODO: supply links to information on markdown
TODO: supply links to information on Itex