You can use images as button icons. Using an image to perform tasks other than submitting data requires attaching a behavior to the form object.
The Image Source dialog box appears.
A image field appears in the form.
To create a submit button, enter Submit in the Image Field text box in the Property inspector.
For more information, see Setting image field properties.
For more information, Attaching JavaScript behaviors to HTML form objects and Attaching custom scripts to HTML form buttons.