what he said, and also you can use youtube to look up how to do that as well. I have been using youtube to learn new editing techniques more often lately so i can slowly improve the quality of my videos
Well, first off it depends what software you use. An easy way to figure it out is to look your softwares tutorial up on yt, but if you happen to use sony vegas 15 there is a blur tool. You simply have to look on the left and drag the setting to the timeline. Hope it helps.