How to get a white background/outline in pictures?

Okay so I love when pictures are outline and they have a white background and I always want my pictures to look like that but going into a paint program and erasing the background can be time consuming and then I worry about if I messed up so I was wondering if there are any good apps for the iphone 4s (for free) that will let me do that?
Here is what I mean by white background
Picture 1: http://instagram.com/...xpKLSpEJB/
Picture 2: http://instagram.com/...-cocbJEFi/

There's no easy way round this or any app that can do that for you, unless you use photoshop which i doubt you would do that if you are looking for an easy fix. So really, there's no simple and easy way to do this without spending the time doing it.