Standard and custom images can be assigned to a command.
Click Manage tab Customization panel User Interface. Find
In the Customize tab, Command List pane, select the command to which you want to add an image.
Do one of the following:
Assign a standard image
In the Button Image pane, under Apply To, select one of the three image assignment options; Small Image, Large Image, or Both.
Select an image from the image list and the image name is assigned to the Small Image, Large Image, or both the Small and Large Image properties of the selected command.
Import and assign a custom image
In the Button Image pane, right-click the list of images and click Import Image.
In the Open dialog box, browse to and select the image file that you want to import and click Open.
In the Button Image pane, under Apply To, select one of the three image assignment options; Small Image, Large Image, or Both. Then select the image you imported from the image list.