You're more then likely going to run out of room with that small style width, but you can try anyways.
I believe the navbar links are being read in the header template... let me know if you can't find them in there... But assuming they are:
Open the admincp and go to;
styles & templates > style manager > edit templates > header
find the following code
Code:
<if condition="$show['registerbutton']">
<td class="vbmenu_control"><a href="register.php?$session[sessionurl]">$vbphrase[register]</a></td>
</if>
add under
Code:
<td class="vbmenu_control"><a href="store.php?$session[sessionurl]">Store</a></td>
<td class="vbmenu_control"><a href="search.php?do=getnew">Today's Posts</a></td>
be sure to replace the a href with the correct link for your forums
As I said, the width of that style is extremely small for fitting all those links in... You may want to take some links out of there...
Anyways, Good luck.
Jonathan