Provide alternative text for a picture
You can specify alternative text for pictures in a Microsoft Office InfoPath 2007 form template. Alternative text appears when a user moves the pointer over a picture, and also helps users with screen readers understand the content of pictures.
Right-click the picture, and then click Format Picture on the shortcut menu.
Click the Text tab.
In the Alternative text box, type the text you want.
Tip The text can be as long as you want, but some Web browsers might be able to display only a limited number of characters.