Create a transparent GIF
You can convert a picture to a transparent GIF directly in Microsoft Expression Web. You convert a picture by selecting one color in the picture to be transparent, and then wherever that color appears, the page background shows through. Each picture can have only one transparent color. If you select a transparent color for a graphic that already has one specified, the original transparent color will no longer be transparent.
If the graphic is not in GIF format, Expression Web first converts the picture to that format. After you add transparency to a picture, the edited picture isn't saved until you save the page. At that time, the Save Embedded Files dialog box lets you choose to either overwrite the original file or save the edited picture to a new file. For more information, see Save an embedded picture.
In your web page, do one of the following.
To edit a picture in your page, click the picture.
To edit the background picture of the page, you do not need to make a selection.
On the Pictures toolbar, click Set Transparent Color .
On the picture, click the color that you want to make transparent.
To save the edited picture, on the File menu, click Save to save the page.
In the Save Embedded Files dialog box, set the options you want and then click OK. For more information, see Save an embedded picture.