To help get you started contributing, we've created a tips for new contributors page, full of helpful links about policies and guidelines and style, as well as some important information on copyleft and basic stuff like how to edit a page. If you need help, check out Help, or post a message in the travellers' pub. If you are familiar with Wikipedia, take a look over some of the differences here.
There are some differences between Wikivoyage and Wikitravel. You may want to look at Wikivoyage and Wikitravel for some of the background, and also at Wikivoyage:Article templates and Wikivoyage:Listings for some of the things we've changed since the fork (notably, we no longer use "Get out", but rather, "Go next", and we use listing templates, rather than listing tags).