Many Web sites have a Web background with a coloured margin on the left hand side of the page.
The Xara Ltd site is one example of this, although on the framed version of the site the sidebar is actually a separate frame. The browser will tile the image both horizontally and vertically, and there's nothing you can do to stop it. The secret to creating a Web page with a sidebar is therefore to create a graphic that's wider than the screen, so that any horizontal tiling of the image takes place invisibly off the edge of the screen. Creating a graphic that's 1300 pixels wide will work on most screens, although you may want to go up to 1600 or more to cope with people viewing your pages on large monitors. The next step is to draw a second rectangle so that it covers only a small section at the left hand end of the first rectangle.