If you go to the downloads section, in the list there is a link to submit a new page for that section.
In this case i assume it's a coop mission:
In that page there is also a link to "How to submit a file
", to help you filling the fields and page info. In this "tutorial" there is also a link to our FAQ: "how to get a file hosted in Armaholic
", with different methods to give us the file (using our public ftp, mails, free webs for hosting files,...)