There are a few different ways to upload a file, it depends on what sort of file you'd like to upload.

Upload Images

Use the Insert / Edit Image button to upload an image. Simply provide the URL of where the image is located or upload an image from your computer.

Ex. Insert / Edit Image Dialog

You can either provide a url of an image or use the Browse Server button to browse for and / or upload an image.
Upload tab is a shortcut to upload an image

Upload FLASH Documents

Use Insert / Edit Flash button to upload a flash (.swf) document. Simply provide the URL of where the flash document is located or upload an image from your computer.

Ex. Insert / Edit Flash Dialog

You can either provide the url of a flash (.swf) file or use the Browse Server button to browse for and / or upload a flash file.
Upload tab is a shortcut to upload a flash file

Upload Other Files

Highlight a portion of  text and use the Insert / Edit Link button to upload any other type of file. (*exluding .php and *.exe files for security purposes).

Ex. Upload a file