The MAP repository
The MSX Assembly Page source code is stored in a Git repository, which you can find here:
Below you will find a few pointers on how to work with Git.
If you have push rights, please be sure to verify your changes on the website after pushing changes to the repository.
The process to get push access is not very well defined, but usually after you’ve submitted a couple of good changes and grown accustomed to the structure of the site, you can get access.
About Git
Git is a distributed revision control system. You can download Git from their website. I recommend you also get GitHub Desktop, an easy to use visual client.
For more information on using Git and GitHub, consult the Git documentation and the GitHub documentation.