This template seems to be made for fixed width , so first locate this in your stylesheet

#indexDefault .centerBoxWrapper {
margin-bottom:0 !important;
padding-top:2px !important;
}

remove padding-top .

then locate this rule in your stylesheet
.mainWrapper {
text-align:left;
vertical-align:top;
width:90%;
}
change width to 1150px .

and most importantly , your site is powered by zencart and not ** URL REMOVED ** . you can remove zencart but you are not allowed to take credit for the code.

hope all helps.