I have booked a train from the Frankfurt Flughafen station. Is this right inside the international airport or we need to take a taxi /shuttle to get there?

Thanks.

It's at he airport - you can walk. Actually there are two stations. Does your ticket indicate the Regionalbahnhof or the Fernbahnhof? You will find signage that leads you to both.

Both stations are walking distance. In fact, that is the only way you can get there - by walkway.

Look at the map:
http://www.google.com/maps/@50.05203...!3m1!1e3?hl=en

The tadpole shaped building on top is the Fernbahnhof for long distance trains while the Regionalbahnhof is located below the Sheraton hotel, but you access it by going underground from inside the airport.

Fernbahnhof as we are taking a train to Basel.

Thank you, that makes it vey convenient.