3 equal column ( full width)

Hi ,
Refer to the attached file, I want three equal column ( full width ) after header and before other items like recent listing.
Because I want to use it for three advertising area for paid feature listing , paid promotion listing and paid agent listing.
And link to their associate post if someone click any of the item in it.
It is similar to 3 column text box ( full width).
But text box is just text.
I want to put the specific listing in it with horizontal or vertical scrollable bar.
Not sure how can I achieve this.
Appreciate any help.
Thanks.