Blog posts & Archives Background Colour change

Hey Sakin Hope your good mate!? My sites back ground colour is white which is great. But on the blog page & other pages I'd like to change the back ground colour of a post to a slightly different off white colour to give my post's that boxed in look. I'd all so like to do the same for the archives widget. this is the current look https://www.dropbox.com/s/7dbzyez32gtvstw/Screen%20shot%202014-03-06%20at%2015.02.43.png & this is a rough mock up of what i'm looking to play around with https://www.dropbox.com/s/226ttyd78p8zsjc/example2.jpg or maybe just a black border around the posts & side bar would be worth a try? cheers brother!! your help is always much appreciated c