I want to upload and use a file
Upload a file
Prepare the file for upload. Make sure the file is exactly as you want it. In the sidebar, under “toolbox”, click “Upload file.” Click “Browse” next to the “Source filename:” to locate the file on your computer (the name of the “browse” button depends on your web browser). Change the “Destination filename:” to something descriptive, if necessary. Fill in the “Summary,” if necessary. Click the “Upload file” button. If it is a large file, you may need to wait several seconds for the upload to complete.
Using images and file description pages
After you've uploaded a file, you can use it in an article, with some special wiki syntax to create the link.
[[File:filename.extension]] For specific size in article [[File:Example.jpg|200px]]
Your file gets its very own “file description page” within the File 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.
With the following command a user can provide a link to the file.
[[Media:name of your uploaded file |The title]]
There is a list of other options you can use. Please visit MediaWiki for more