The blur background is a photography 'trick', physics of light, aperture and lens. To blur the background, use a large aperture (small f-stop), but be careful, if you are using an SLR or digital SLR, too small an F-stop may give you a picture with Dept of field (the deprt that is in sharp focus) so shallow that only part of the subject is sharp.. let's say you shoot a dog and focus at the eyes... if you use too small an f-stop, you may end up with a picture where only the eyes are sharp whereas the nose and the rest are blurred. But if you are using consumer digital camera with lens that cannot be changed, this shouldn't be a problem... but the intensity of the of blur is limited, even if you use the smallest F-stop that is available. Other factors that affects the DOF is the distance between you and the subject and the subject to the background, as well as focal length of the lens.
To achieve black and white, use photoshop and desaturate the image by clicking image->adjust->desaturate or converting the picture to grey scale.
Images with parts in coulour is done with layers in photoshop... There are a few was to do it. One way will be creating a new layer on top of the image and copy the image onto the new layer, so that you have two layers that are exactly the same. Next, desaturate the top layer. Working on the desaturated top layer, Select the area you want in colour with the appropriate selection tools. When done, delete away the parts, the coloured layer below will show through. Now, you got an image with coloured and B&W elements.
This is just a brief explanation, if there's anything more, ask ask.
;p
