How to make the border white around an instagram photo?

[Olivia]

Hi well I have a new camera and I wanted to take some pictures that will be tumblr-ish for my instagram profile which will be based on tumblr things. But I really want to know how all these tumblr girls make their pictures with a picture and then like a white border/background around It. It makes it look like a tumblr type thing like there's this new account called 'awk0_sloths_' and she has pictures with those white background/border things. But the pictures are not her photos so she doesn't know. I've tried squaready and whitagram but there's not enough white background around it. So check out 'awk0_sloths_' account and if you know how they do it or what app it is, please comment! The app which I find is correct I will reward you with 10 points and ill follow you!! So please help!! Thankyou