Edit /templates/default/subtemplates/index.tpl.inc

... and /templates/default/subtemplates/entry.tpl.inc

note: I couldn't post this because one of the lines was too long & had to add some spaces, so it won't exactly match the template.

You can use the [code]...[/code] for this purpose:

<strong>{if $data.$element.user_type==2}<span class="admin" title="{#administrator_title#}">{$data.$element.name}</span>{elseif $data.$element.user_type==1}<span class="mod" title="{#moderator_title#}">{$data.$element.name}</span>{else}{$data.$element.name}{/if}</strong>

... or [code=html]...[/code]:

<strong>{if $data.$element.user_type==2}<span class="admin" title="{#administrator_title#}">{$data.$element.name}</span>{elseif $data.$element.user_type==1}<span class="mod" title="{#moderator_title#}">{$data.$element.name}</span>{else}{$data.$element.name}{/if}</strong>

... or [code=smarty]...[/code]:

<strong>{if $data.$element.user_type==2}<span class="admin" title="{#administrator_title#}">{$data.$element.name}</span>{elseif $data.$element.user_type==1}<span class="mod" title="{#moderator_title#}">{$data.$element.name}</span>{else}{$data.$element.name}{/if}</strong>

More about the syntax highlighter here...

Alex