You can personalize your channel by using logos and titles or a background image. The image sizes are very specific and must take into account different sizes and resolutions of computer screen as explained in the following video.
Creating channel logos and backgrounds
Parts of the background can be defined as hotspots allowing them to be linked to websites. For example, your background might contain a sponsor's logo; by defining it as a hotspot you can create a link to their website.
Your questions answered
I don't see the logo when I add my background?
The background replaces both the logo and the channel title so, as shown in the video above, you need to include these elements in your image. However, the logo will remain the default logo for new collections you create.