Do the following steps:
1) Open "RAWR-Template-0.1.3.tpl" using notepad or any text editor.
2) Locate the following section (you can search for the word "navbar"):
<div id="navbar">
   {.if not|%user%|<div class="bigBtn"><a href="~login"><span>{.!lv_login.}</span></a></div>.}
   <div class="bigBtn">
      <a href="javascript:void(0);" onclick="window.open('/~progress','{.!lv_transfers.}','width=300,height=500,left=100,top=100,scrollbars=1,resizable=1');" class="hide"><span>{.!lv_transfers.}</span></a>
      <noscript><a href="/~progress" target="_blank"><span>{.!lv_transfers.}</span></a></noscript>
   </div>
   {.if|{.get|can upload.}|<div class="bigBtn"><a href="~upload" title="{.!lv_uploadTitle.}"><span>{.!lv_upload.}</span></a></div>.}
   {.if|{.{.!btn_back.}=on.}|{.if not|{.%folder%=/ .}|<div id="backBtn"><a href=".."><span>{.!lv_back.}</span></a></div>.}.}
        <div class="bigBtn"><a href="https://www.google.com/"><span>Google</span></a></div>
        <div class="bigBtn"><a href="https://www.example.com/"><span>Example</span></a></div>
</div>
3) Add the text marked in red color, for example, this adds a link to Google.
4) If you need another button, you add another line there (like the text marked in blue color):
        <div class="bigBtn"><a href="https://www.example.com/"><span>Example</span></a></div>
I've attached an example, so you can see the changes (it's easy to add more buttons if you need it).
Please report back if this solves your question. 

Cheers,
Leo.-