To include a link to an uploaded file in a webpage:
Go to the File Manager module in the admin console. (It is one of the items in the pull-down menu at the top of the admin console.)
Click on the file-type icon to the left of the File Description. The following dialogue box will appear.
Copy everything from the box labelled Direct URL.
Click on Cancel.
You can now use the link in your page.
Take care not to use a link to a members-only file in a public page. If you want a file to be downloadable by guests, make sure that it's set to Public in the File Manager.
If you want a file to display directly in the browser, change the part that says "action=download" to "action=inline". This is particularly useful for pdf files.