If file uploads are enabled, you can upload certain types of files to the wiki. This is particularly useful for uploading images, which you want to place on an article, but you can also upload other types of files.
If it is a large file, you may need to wait several seconds for the upload to complete. Note that very large files may be blocked due to wiki file size limits.
After you've uploaded a file, you can use it in an article, with some special wiki syntax to create the link. See Help:Images.
Your file gets its very own "file description page" within the Image namespace of the wiki. You should edit this page to provide more information about the file. For example, many public wiki projects are quite sensitive to copyright issues, and so you should explain where you got the file from, and what its copyright status is, on the description page. Any other useful descriptive notes could also be added there.
There are a number of special pages to help you view and manage files which have been uploaded. Go to Special:SpecialPages (in the left nav) and then see...