The trick, as Allen says, is to find somebody who wants to use what you know how to do more than they want their money!
If you want to do it "moonlighting" while you maintain a regular job, just tell everyone you know that you are offering services. Just make sure that you are not in direct competition with your employer.
If you want to do this full time as a living, it is more complicated. I don't know about India, but in the US starting a business is easy. For a sole proprietor, you simply say "I am now doing business as Riyajahamad Programming Service" and it's done. However, you are then personally liable for any business expenses and liabilities, so you probably want to look into some sort of limited liability structure to cut down on your exposure.
The first step is to talk to someone you know in a related field, or even a potential competitor, who has successfully gone off on their own. Find out the going rates, and network - talk to all potential clients.
Good Luuck.