If you need to upload a file, click the button that is labeled "Insert Link/Upload File" in the diagram above. Then click the Upload tab on the next screen. Simply select your file from your local directory using the Browse button, and then click Send it to Server to upload your file.
Then you can click OK to automatically create a link to your file. To insert a link, click on the same button, and specify your link in the first tab. Click OK when done.