AVOTWiki is a web-based collaboration / web authoring / document management / knowledge base system, where you can edit (add comments, attach files, etc.) most pages.
If you are used to this form of collaborative web development - and you are already registered - jump right in; otherwise check out the help page first.
Follow that up with a visit to the TWikiTutorial and then try out what you've learned at the Test web.
AVO project members and others who have already registered and are interested in defining the functionality and usage of Virtual Observatories, you can jump straight into creating Science Problems and Use Cases if you'd rather.
AVO-TWiki