First select the second menu option - "Upload and Manage Files" from the main iTunesU menu to see the screen below.

A new window will open to display the "Upload and Manage Files" screen (shown below). Video and audio recordings can be uploaded manually by selecting the "Add New File" option at the bottom left of the screen.  

When the Add New File option is selected a new File Upload window opens. Browse through the files on the computer or the network, select the desired file (as shown below) and click the Open option.

Once the desired file is selected and opened, iTunesU starts the upload process immediately. While the file is uploading, the percentage of competion is shown alternatively with an "In queue" message.

Once the upload is complete, the newly added file and a confirmation message are shown as seen in the image below.