That’s a commercial theme, so you’ll really need to contact them for support — commercial themes are not generally supported here.
That said, I looked at the CSS and found that it’s a bit complicated and messy in the CSS for that section. You’ll have to play around with it and see if you can get it to look right. It’s a flexible width page so theoretically you can make it as wide as you want. But whether or not it works well (appearance and for users) is another question.
The first thing is that the following CSS sets the width of that section to 630px:
line 1611:
.right_sidebar #main .content {
overflow: hidden;
width: 630px;
}
But each of the columns is set to 219px here:
line 2479
.portfolio_four_columns li {
width: 219px;
}
So it’s impossible (simple math) to fit four columns unless you change the width of the first part.
Also, the following 2 CSS declarations are affecting the layout of that section — so you might need to change these too:
line 2476:
.portfolios .portfolio_four_columns {
margin-right: -28px;
}
line 2488:
ul.portfolio_four_columns li {
margin-right: 28px;
}
Good luck!