when i try to edit map data, there is no attribute called Gas Station please add it, here in india we called Petrol Bunk instead Gas station pl note it.

Many countries that have English as an official or commonly-used language have different terms for different things. OpenStreetMap tends to use British English, because that's where the project was started. If you look through the wiki you'll see lots of pages that say "OSM uses X because that's what British English does".

In this case the actual tag used is "amenity=fuel" - designed to work in Britain (where we have "Petrol Stations"), the USA ("Gas Stations") and presumably also in India. In the online editor, it's listed as "fuel" under the "transport" category (as Richard has noted).

If you're starting out editing, you'll probably have lots of questions like this. Everything's documented somewhere, but unfortunately where isn't always obvious to someone just starting with the project, although it's getting better. The main page of the wiki now has links to "places to get help from" (including this site and the Beginner's Guide pages, which if you've not already seen are definitely worth reading. The Contact page is also useful, as is (if you just want a quick answer to something) IRC - just join the channel and ask a question. There are also several mailing lists including one for new users that is perfect for questions like this one.

You want the 'Fuel' preset: