To contribute to the project, make a merge request at https://gitgud.io/archaeme/fediwiki. Alternatively if you want to contribute from elsewhere (e.g. Github, Bitbucket, personal repo, etc.) contact @archaeme or mitchell and either of us will be willing to take a look at your changes. Once merged, the changes will take effect on the live server within an hour after they're pushed to the repo.
This wiki is made up of Markdown files. Here's a good reference for the Markdown syntax. To create a new page, simply make a new file with a .md extension and use whatever text editor you prefer. Preferrably the files should use UNIX-style line endings (just newline chracters and no carriage returns).