I have an apple iPad 2 and want to use data card for Internet connection at places where there is no wifi facility available

Is it a cellular equiped model? If it is, contact a local cellular compnay that supports iPad. If not, you cannot convert it. You're only option would be to purchase a MiFi unit.

If your iPad is a Cellular model then you can buy a sim card from your carrier and place it in the iPad's sim tray and have it connect othe cellular network t get internet access.

If your iPad is a Wifi only model it can;t do this. However, you can then either use your Phone as a hotspot if it supports it and your cell carrier suports the feature, or buy a Mifi device.

A Mifi device is a small cellular based router. It connects to a cellular network, and provides a small wifi network for other devices to connect to and use that Cellular connection.

Contact your cell carrier to find out what they offer in either case.