<div class="leftcolumn">
<{foreach item=block from=$xoBlocks.canvas_left}>
<{include file="$theme_name/theme_blockleft.html"}>
<{/foreach}>
</div>
I guess you can change it like this to put blocks one after another in a horizontal direction
<div class="leftcolumn">
<{foreach item=block from=$xoBlocks.canvas_left}>
<div style="float:left;"><{include file="$theme_name/theme_blockleft.html"}></div>
<{/foreach}>
</div>
but that's only my suggestion.
you can also use trabis' 'blocks anywhere' tool to place your blocks wherever you want in your theme.
hope that helps
deka