A flight simulator is not always an easy task. It depends on how realistic you want the visual scene and the aircraft dynamics to be. As Gavin says you would normally model aircraft and terrain using other software and then load these into OpenGL. The dynamics of the aircraft are a whole new set of problems not related to the visual scene, again it depends on how realistic you want the flight model to be.
On the graphics cards you can use just about anything to start with. Once you increase the complexity of your simulation you may wish to invest in a card (if you haven’t got one already) that has hardware support for the things you use. Almost all cards have 3D accelerators and such these days.
Don’t know about training in India though. You could start by doign some of the many tutorials on the web. A good start would be nehe.gamedev.net.
[This message has been edited by thelamberto (edited 03-07-2002).]