How to take a multi depth focus photograph using a Digital SLR camera?

SLR cameras tend to focus on the subject and the background becomes un-focussed. How to take a photo with all things in the foreground and background in focus???

the previous answer is quite correct. but one thing you might what to know is this: it isn't the camera that cannot focus on "everything", it is the lense. if you have a wide anlge lense, then you can focus on most everything in your picture. zoom lenses (i.e. : 50mm to 200m, 70mm to 300mm, ...) will only be able to focus on one subjet. once again, everything depends on the quality of the lens (most compagnies have diferent series of lenses). if you are taking group pictures, landscape, ... you should get a wide angle lens (you should be able to focus on everything) and if you have the money, you should get a 'wide angle zoom' lense.

The tecnical term is depth of field. You'll get the most in focus if you use the higest aperture number.
Landscape photographers tend to use the second highest aperture number on their lens, because the very highest setting useually leads to some degradation of the image quality.

Most good digital SLR cameras have more than one focussing system. They may default to focussing in on the main subject but there are probably a whole bunch of other modes that might give a better result. The most common are various numbers of multi-target focussing schemes where the camera looks at several different spots in the image to focus in on and splits the difference to try to get the whole shot in focus. Also, they might allow you to choose a specific spot in the shot as the central focus point. My camera, for example, as a small joystick for this purpose. Many times, I place the subject off center for various reasons. To maintain correct focus, I can use the joystick to place the focal point back on my subject instead of in the center of the shot (where there might not be anything within the same distance as the subject). Nice.

Make sure you have enough depth of field when using a multi-target focussing scheme (or else everything might be equally out of focus...hehe). This is mostly controlled by the aperture size. A larger f-number means a smaller aperture. This creates more depth of field (the range of distances from the lens for which objects are in focus). Most cameras have an aperture priority mode. Select the f-number you want and the camera automatically selects the other variables correctly to get the right exposure.