Single click the desired equipment type on the left-hand menu, then click on the first link on the right. For example, if you are adding a radiation survey meter, click on "Meters" directly under the bold-faced "Meters" heading. This will take you to a table view of all of the radiation survey meters.
Click "+Add" in the menu.
Fill out the desired information, add the equipment owner under "Custodians", and then click "Save"