You will need to rearrange where the blocks coding are in your theme. The below is from the default theme.html and hopefully it will give you the idea of what you can do.
<td id="centercolumn">
<!-- Display center blocks if any -->
<{if $xoops_showcblock == 1}>
<table cellspacing="0">
<tr>
<td id="centerCcolumn" colspan="2">
<!-- Start center-center blocks loop -->
<{foreach item=block from=$xoops_ccblocks}>
<{include file="default/theme_blockcenter_c.html"}>
<{/foreach}>
<!-- End center-center blocks loop -->
</td>
</tr>
<tr>
<td id="centerLcolumn">
<!-- Start center-left blocks loop -->
<{foreach item=block from=$xoops_clblocks}>
<{include file="default/theme_blockcenter_l.html"}>
<{/foreach}>
<!-- End center-left blocks loop -->
</td>
<td id="centerRcolumn">
<!-- Start center-right blocks loop -->
<{foreach item=block from=$xoops_crblocks}>
<{include file="default/theme_blockcenter_r.html"}>
<{/foreach}>
<!-- End center-right blocks loop -->
</td>
</tr>
</table>
<{/if}>
<!-- End display center blocks -->
Move the center center blocks table row to below the center left and center right blocks row. To where I have placed the Quote below. That should work or get you started.
<td id="centercolumn">
<!-- Display center blocks if any -->
<{if $xoops_showcblock == 1}>
<table cellspacing="0">
<tr>
<td id="centerLcolumn">
<!-- Start center-left blocks loop -->
<{foreach item=block from=$xoops_clblocks}>
<{include file="default/theme_blockcenter_l.html"}>
<{/foreach}>
<!-- End center-left blocks loop -->
</td>
<td id="centerRcolumn">
<!-- Start center-right blocks loop -->
<{foreach item=block from=$xoops_crblocks}>
<{include file="default/theme_blockcenter_r.html"}>
<{/foreach}>
<!-- End center-right blocks loop -->
</td>
</tr>
Quote:
<tr>
<td id="centerCcolumn" colspan="2">
<!-- Start center-center blocks loop -->
<{foreach item=block from=$xoops_ccblocks}>
<{include file="default/theme_blockcenter_c.html"}>
<{/foreach}>
<!-- End center-center blocks loop -->
</td>
</tr>
</table>
<{/if}>
<!-- End display center blocks -->