Simple Press Forum on Full width page on monochrome

I am trying to make post content (Middle section) on the no sidebar no comment page wider so that my forum (simple press forum) can fit on the full width of the page… I have done it before on other themes following the instructions provide by SPF (http://simplepressforum.com/creating-a-wordpress-page-template/). But I can seem to do the same with this theme, it is a bit more complicated than the other themes. I was wondering if anyone can help me out. Thanks