How to Obtain Trade Mark (TM) for a Word ??

Hello guyess...

In Little trouble...

We have a chain Cyber Cafe systems... The Name is Doorer Sathi...

Now many times i have seen that the name is been used and some time missudes by others...

Now i would like to Register the Word "Doorer Sathi" and obtain Tread Mark for it so that we can procced if any miss use is going on...

Now How obtain a Tread Mark ??

Where to approch and Whom to contact.. ??

I am a Kolkata resident

Any help will be Appreciable

Thank you..