This tutorial assumes that Development mode is enabled, you have already uploaded your logo using the File and Media Manager.

Edit your Layout

1. Under the Layout menu, click on the Layout editor link
2. Click on the Editing: Homepage link and choose Site Header
   
3. Click the edit link next to Site Logo
   
4. In the window that appears, Select the image that you uploaded using the File & Media Manager
   
5. Click Save changes