Step 1: Create a custom logo. If you want to create a drop-in replacement for the default logo, create a 248x50 logo with a transparent background and save it as a PNG. In the video that accompanies this blog post, you'll see that I have created a 248x50 transparent PNG that has the logo of a fictitious company named "myCorp++".
Step 2: Save this custom logo to sonatype-work/conf. It doesn't make much difference where you save this file, but since this is something you are customizing it does make sense to save this file somewhere under your sonatype-work directory.
Step 3: Install the Nexus Branding Plugin by copying nexus-app/runtime/apps/nexus/optional-plugins/nexus-branding-plugin to nexus-app/runtime/apps/nexus/plugin-repository.
Step 4: Edit the nexus-app/conf/plexus.properties file and add the configuration variable "branding.image.path". Use the variable nexus-work which is defined in this file to refer to the sonatype-work/nexus directory.
Step 5: Restart Nexus.
Step 6: Admire your custom logo.
