border around div.main??

Hi, i feel like a right idiot asking all these simple question that i did know the ans to but have been away for ages,

ok so here goes, im trying to pop a border around the div.main part of my website but for some reason i cant seem to find the right file to do this, any help would be great, thanks, plus if it can be so it's just the index.php page that has the border around the div.main then that would be even better.

Thanks

Charlie 

You can try this,

1)

open file templates/base/_sub_header.html

find this code: <div class="main" style="border:0px; width:__main_div_width__;">

edit to this: <div class="main" style="width:__main_div_width__;">

2)

open file templates/tmpl_uni/css/index.css

add this code to it:

.main {
    border:1px solid #CCC;
}

3) Delete Cache

(If you don't use UNI add it to your template)