Hope you are doing fine.
>>>Here is the link to a site on which you have to submit your application:- www.bis.org.in
Usually, the process is not very easy, the maximum time we have to go through the agents which charge little. You can find such agents from Justdial, look for Delhi based agents. If your manufacturer has CE certificate then it also works as BIS.
To get BIS you also need some test report from the manufacturer. As most of them have test reports for their products. Ask manufacturer if he has any.
Let us know if you need help with anything else!