How to add SMTP mail folders on Favorite bar in Mail for OS X ML

Hi guyz may be this is the dumest question but today i find out that i dont want side bar open all the time in mail app all the inboxes, sent folders showup in favorite bar, but there is one problem i have multiple email accounts and to see older mails from their folders i have to open side bar, which i really dont want to do anymore, is there any solution to add my email folders in fav bar so i can see them right there, i tried to look in every option but couldnt find anything.