1. Click the image to select it.
2. If the Graphics Toolbar is not already in view, use View> Toolbars>
3. On the Graphics Toolbar, click on the Set Pet Pattern icon and choose
a pattern (usually solid)
4. On the Graphics Toolbar, click on the Set Line Width icon and choose
a line width.
5. On the Graphics Toolbar, click on the Set Color icon and choose a color.
Your image should now have a border of the pattern, thickness, and color
Just by the way, it's often suggested that referencing images is a better way to work with FrameMaker. Use the Save as picture option in Word to save the picture as a separate file, then File > Import in FrameMaker and the Import by reference option.