To use the Image Optimizer to make an image with a transparent background:
- In the Web menu, select Image Optimizer.
 - In the Image Optimizer dialog box, select the GIF file format button.
 - In GIF Options tab, select the Transparency check box.
 - Go to the Mask Options tab.
 - Select "Pick color" in the Mask option and click "Add to Mask," then choose
 - color directly from the preview window.
 - Click "Save As" to save the optimized file.