Changing your Image logo and sitename styling can easily be done within the Design panel.
1. Select the Design tool from the gray navigation bar. Under the Sitewide section in the right-hand menu, click on Header & Logo.
2. Select and Upload your image/graphic logo in the blue upload box under the Logo menu. 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.
3. Select Save and Publish.
Note: You can change the size and alignment of your logo, as well as add a site name too.
4. Under the Sitename menu, choose one of over 100 Adobe TypeKit fonts and style the text name of your website.