White Balance
 

Hello - Could anyone give me some idea about how to use the white balance feature on a DSLR? Please also let me know in which occasions do I need to use it.

I shoot mostly outdoors under natural light, and must admit I tend to leave it in 'auto'. But, I shoot RAW only and so it is an easy job to correct any colour casts in post-processing.
If you are shooting under particular lighting conditions, for example deep shade, tungsten lighting, fluorescent light, you will get a colour cast because of the light's colour temperature. Setting the appropriate white balance for the lighting should minimise this, but as I say, if shooting RAW it is easily changed anyway. Only a major issue for jpegs straight from the camera would be my feeling...

The white balance settings can be changed too, to set the mood of an image. For example, early mist on a lake, using the tungsten setting gives it a cold, bluer winter feel. Experiment and see the difference with the various settings.