Well, page 59 in the manual... You have to do an animation for the object you want to blur. And then render a frame of this animation (or the whole sequence of course). Keep in mind that the start or the end frame of an animation do not have any blurring because there the speed is zero. So you have to render a frame somewhere in between. The rest are more or less render settings. You need to render in broadcast or higher. Only then blur is available. More or less because the amount of blurring depends on the speed of the object, in relation to the camera. So it sometimes needs a little tweeking there too. AND, effects like that (motion blur, dof etc) will increase the render times a lot. So don't be surprised...

One day your ship comes in - but you're at the airport.