1. Navigate to Confluence Admin >> Custom HTML
2. Click Edit

3. Add the following to At the end of the HEAD:

   <script>
   AJS.toInit(function(){
       AJS.$('.aui-header-primary .aui-nav').append('<li><a href="http://www.atlassian.com" class=" aui-nav-imagelink">Atlassian</a></li>');
   });
   </script>

   The example above will add an "Atlassian" link to the top navigation bar
   
   

To add multiple links:

1. Do the same as for a single link, making sure you follow the same format as below, all additional link items must be on the same line with no hard returns or spaces between them.
   
   

<script>
AJS.toInit(function(){
    AJS.$('.aui-header-primary .aui-nav').append('<li><a href="http://www.atlassian.com" class=" aui-nav-imagelink">Atlassian</a></li><li><a href="http://www.google.com" class=" aui-nav-imagelink">Link2</a></li><li><a href="http://www.google.com" class=" aui-nav-imagelink">Link3</a></li>');
});
</script>

The example above will add two new links "Link2" and "Link3" to the navigation that both link to www.google.com

To add third-party plugin link:

1. Install the plugin.
2. Do the same as for a single link, making sure you follow the same format as below.
   
   

<script>
AJS.toInit(function(){
    AJS.$('.aui-header-primary .aui-nav').append('<li><a href="/plugins/targetedsearch/settings/configurefilters.action" title="Search Filters">Search Filters</a></li>');
});
</script>

The example above will add a third-party plugin 'Search Filters' link from "Brikit Targeted Search for Confluence"  to the navigation bar.