From Envirowiki

Red links on envirowiki point to pages that haven't been written yet. If you click on a red link, you will be taken to the page and you can begin to create it. If you don't feel like adding something to that specific page, just click back, and browse to somewhere else.

Don't be afraid to put content up on envirowiki. Anything is helpful, as it provides a base from which others can work. Small facts, links to relevant articles, random thoughts - even if you're not sure they're correct, or if they are completely wrong, as this should provide an additional incentive for other envirowiki visitors to correct and expand the information on the page.

[edit] uses

Red links are created when ever an internal link is created (with [[double brackets]]) to a non-existant page. As soon as any content is added to the page, the link turns blue. Red links are useful, because envirowiki's software (mediawiki) takes note of the number of red links and tallies them up on the Special:Wantedpages page, where you can see what pages are most requested by other envirowiki pages.