Navigate to the asset you want to add usage to and click the asset to launch a modal window then click the Edit button:

Click the Add Usage tab:

1. Select the channel where the asset will be used from the drop-down list.
2. Enter the URL where the asset will be used. If it will be used in print, leave this field blank.
3. Enter the title of the article/project that the asset will be used for.
4. Select the date this asset will appear from the calendar.
5. Click the Save button to add this usage when done.

If you need to remove a usage, click the trashcan next to the usage in question:

Click yes on the next dialog box: