I am a new DSLR user. Whenever I click a picture using Manual mode the picture is pitch black. You cannot see anything. Which setting should I change? How can I overcome this problem? It's only like this in the manual mode.
There are 3 things that control how much light enters your camera: Aperture, Shutter Speed and ISO - to get a properly expose picture you need to balance those 3 with the amount of light you have.
If you are shooting outside in direct sunlight start with Aperture:f/8, Shutter Speed 1/400 and ISO 100 (those are middles-ish-of-the-road values chosen according to the "sunny 16 rule", there's nothing magical about them, they are just a sensible starting point to test if your camera is working).
The settings above should give you a close-enough exposure for subject in direct sunlight - if you use them you should see an image and not get black picture - if you still get a dark image slow down your shutter (for example to 1/200, then 1/100...), if the picture is too bright make it faster (1/800...).
After you see you can actually get an image learn how to use your camera's light meter - you should see inside the viewfinder a scale with an arrow, that arrow will tell you if the camera thinks you settings will make the image too bright or two dark - to get the what the camera thinks is a right exposure play with the aperture/shutter speed/ISO settings until the arrow is right in the middle pointing the the zero.
The whole purpose of manual mode is to let you override what the camera thinks is the right exposure, so you don't need to take every picture on the exact middle - but you need to be able to quickly and easily set the expose based on the meter before you can effectively override it.
Simple answer: don't use manual mode.
I think there's a prevailing attitude among some camera owners that if they're not in manual mode, they're not doing proper photography. Some people seem to believe that professional photographers always shoot in full manual mode, even if they are taking snapshots of their daughter's friend's birthday party, for example.
Neither is true. Manual mode is specifically helpful for when you want to be able to set a particular aperture and shutter speed. If you are not in a specific situation where you want a specific aperture and shutter speed, you don't want manual mode.
When you shoot in full manual mode you are fully responsible for exposing the picture correctly: making it not too light or dark. The camera will not help you at all. If you shoot in manual mode but complain that the picture is too light or too dark, you are putting the cart before the horse: the whole point of manual mode is for when you know how to set the exposure better than the camera would if you let it choose them automatically. Using manual mode should start with knowing what aperture and shutter speed will result in the desired exposure.
What's happening in your situation is that you are using full manual mode but have not taken the care to choose an aperture and shutter speed that would result in a correct exposure.
The long answer to this is to teach you all about aperture and shutter speed and how exposure is calculated.
But the more concise answer, in my opinion, is just to advise you to use auto mode.
Professional photographers venture away from auto mode because they want to achieve a specific effect by using a particular shutter speed or aperture (or both). That is, they understand what effect a particular aperture or shutter speed has on a picture and want to exploit that. It doesn't sound like you're in this position since you expected the camera to get the exposure right.
If you would like to learn more about the effects of aperture and shutter speed, by all means do so. Also check out the Aperture-Priority and Shutter-Priority modes on your camera, as they allow you to have full control over just one of these settings at a time while the other one is adjusted automatically by the camera.