This tracking cant be done using colors as some people may be bald,also they might be wearing caps.
Please suggest me some proper websites.
Thanks in advance.
This will require some trial and error and original work.
To start with, I often take a background image without people or the objects I wish to detect. This backgroun image can be subtracted from the image from the camera to help clear out the background. A simple of example of this can be found in this blog post: How to Make a Webcam Intruder Alarm with Mathematica—Wolfram Blog
Actually writing software to detect that something is the top of a head might be harder and I’m not sure what the example video/images you are using looks like. Posting a simple example will help people understand your problem better.