You want it to kinda look like XenForo where its directly under the header and the breadcrumbs are to the left of it? Be sure to make a backup before starting just in case.
You will need to edit two templates. FORUMHOME & navbar. To do this do the following:
1. Login to your AdminCP.
2. Scroll down on the left side and find Styles & Templates > Style Manager. Click on the Style Manager link.
3. Find the style you want to edit in the list and click the drop down menu on the far right and choose "Edit Templates" That list of templates in the box is where you will find the templates that I stated.
4. Find the template you need to edit & double click on it to open it, then do your edit and save.
To accomplish that try the following: Open your FORUMHOME template and find:
<vb:if condition="$show['sidebar']">
<div id="content_container" class="{vb:raw $sidebar_class} <vb:if condition="$show['sidebarposition'] == 'left'">contentright</vb:if>">
<div id="content" <vb:if condition="$sidebar_class">class="{vb:raw $sidebar_class}"</vb:if>>
</vb:if>
And delete it and then save the template. now open your navbar template and find:
<div class="body_wrapper">
And replace it with:
<div class="body_wrapper">
<vb:if condition="$show['sidebar']">
<div id="content_container" class="{vb:raw $sidebar_class} <vb:if condition="$show['sidebarposition'] == 'left'">contentright</vb:if>">
<div id="content" <vb:if condition="$sidebar_class">class="{vb:raw $sidebar_class}"</vb:if>>
</vb:if>
See attachment for result.