The following tutorial explains how you can replace the logo in Business4 on a Plone 4.2 website.
Business4 diazo Plone Theme uses Plone 4 default logo (Sunburst Theme logo), it is displayed at the top right area:
You can replace this logo with your own one via Zope Management Interface. Go to Site Setup:
Follow Zope Management Interface link:
Now select portal_skins -> sunburst_images. This folder contains logo.png image:
This is a default Plone 4 Theme logo image. To set your own logo - press Customize button:
Press Browse button to select the your own logo (maximum height is 75px) and then click on Upload:
Now you see your new logo.png image, and it is automatically put into custom folder:
Now when you return to Plone interface, you'll see new logo image (Quintagroup logo):