Go to the language and phrases and search for getnew_tab, click edit and then enter Store at the text box and save the changes.
To replace the link with your custom link, go to the navbar edit and replace the following code:
{vb:raw template_hook.navtab_middle}
<vb:if condition="!$vboptions['selectednavtab'] AND THIS_SCRIPT == 'search'">
<vb:if condition="$show['member']">
<li class="selected"><a class="navtab" href="search.php?{vb:raw session.sessionurl}do=getnew&contenttype=vBForum_P ost">{vb:rawphrase getnew_tab}</a>
<ul class="floatcontainer">
<li><a href="search.php?{vb:raw session.sessionurl}do=getnew&contenttype=vBForum_P ost">{vb:rawphrase new_posts_nav}</a></li>
<li><a href="search.php?{vb:raw session.sessionurl}do=getnew&contenttype=vBForum_S ocialGroupMessage">{vb:rawphrase new_group_messages_nav}</a></li>
<li><a href="search.php?{vb:raw session.sessionurl}do=getnew&contenttype=vBForum_E vent">{vb:rawphrase new_events_nav}</a></li>
{vb:raw template_hook.navbar_getnew_menu}
<li><a href="forumdisplay.php?{vb:raw session.sessionurl}do=markread">{vb:rawphrase mark_forums_read}</a></li>
</ul>
</li>
<vb:else />
<li class="selected"><a class="navtab" href="search.php?{vb:raw session.sessionurl}do=getdaily&contenttype=vBForum _Post">{vb:rawphrase getnew_tab}</a>
<ul class="floatcontainer">
<li><a href="search.php?{vb:raw session.sessionurl}do=getdaily&contenttype=vBForum _Post">{vb:rawphrase todays_posts}</a></li>
<li><a href="search.php?{vb:raw session.sessionurl}do=getdaily&contenttype=vBForum _SocialGroupMessage">{vb:rawphrase daily_group_message}</a></li>
<li><a href="search.php?{vb:raw session.sessionurl}do=getdaily&contenttype=vBForum _Event">{vb:rawphrase daily_events}</a></li>
{vb:raw template_hook.navbar_getdaily_menu}
<li><a href="forumdisplay.php?{vb:raw session.sessionurl}do=markread">{vb:rawphrase mark_forums_read}</a></li>
</ul>
</li>
</vb:if>
<vb:elseif condition="$show['member']" />
<li><a class="navtab" href="search.php?{vb:raw session.sessionurl}do=getnew&contenttype=vBForum_P ost">{vb:rawphrase getnew_tab}</a></li>
<vb:else />
<li><a class="navtab" href="search.php?{vb:raw session.sessionurl}do=getdaily&contenttype=vBForum _Post">{vb:rawphrase getnew_tab}</a></li>
</vb:if>
{vb:raw template_hook.navtab_end}
And replace it with:
<li class="floatcontainer"><a class="navtab" href="url to your store page">{vb:rawphrase getnew_tab}</a></li>
This will show the store button to members and guests alike. If you want to show it to members only, then use this code instead:
<vb:if condition="$show['member']">
<li class="floatcontainer"><a class="navtab" href="url to your store page">{vb:rawphrase getnew_tab}</a></li>
</vb:if>