You can add/change your logo on your liveBooks website, here is how:
1. Select Design from the navbar
2. On the Sitewide section of the Design panel, select Header & Logo
3. Select and Upload your logo in the blue upload box. If the logo looks pixelated, uploading a larger logo will often solve the issue. A logo of around 1000 pixel width will work with most retina displays.
4. Select Save
5. Select Publish
Note: You can change the size and alignment of your logo, as well as add a site name too.