Getting Q&A pages to show up in a page that uses my theme's page defaults/styles

Could someone please provide me simple step-by-step instructions as to how I get my questions page to show up (ie, use) my site's template for a full-width default page. Do I add text from my theme's page .php file to the plugin .php code, or is it the other way around? And...specifically where would I plop in the code, wherever I'm plopping it in. THANKS!