To access the file area, start a page edit (usually on the page which will reference your new file) and hit the "file manager" link. The file manager will open in a separate window. Please read the policy and disclaimer carefully.
The file manager shouldn't need much explanation, just find an approprate directory for your file (or make a new one) and upload.
The root directory of the file manager maps to
Files:wiki_insecure/. For example here is Files:wiki_insecure/test.txt.
If you have Lua-related packages that do not fit within the public area's policy or you would like to distribute securely on lua-users.org, contact JohnBelmonte.