In the modern world, picture editing can be performed on virtually any home computer. While a free program like Microsoft Paint may not have all of the bells and whistles of a more expensive program, it can be used to get simple editing jobs done. Microsoft Paint does not technically have any "blurring" tools. However, on the version of Paint that comes with Windows 7, it is possible to achieve a blurring effect using some of the other tools.
Open the picture that you wish to blur using Microsoft Paint. Click the menu tab in the upper left corner, and choose "Open" from the menu that appears. Find the picture you wish to blur in the pop-up window, click on it and then click the "Open" button at the bottom of the pop-up window.
Select the rectangular tool in the "Shapes" menu at the top of the screen.
Click on the upper left corner of the picture, and drag the transparent rectangle over the entirety of the picture.
Select a colour for the blur shading. Click the "Color 2" tab at the top of the screen, and then click on a colour from the "Colors" menu to use for the shading. White or grey tend to be good colours for blur shading, although other colours can yield interesting results.
Click the "Fill" button beside the box of shapes. The "Crayon," "Marker," "Oil," "Natural pencil" and "Watercolor" options will all blur the picture in different ways.
If this type of blurring is not what you had in mind, there are a handful of free programs that can blur pictures in a different manner than Paint. Gimp, Paint.Net and Photoscape are all free photo editors (see Resources.)