how to use IIFL trade terminal on Mac book air

If you are referring to downloading and installing https://ttweb.indiainfoline.com/trade/Downloads.aspx it appears that is a Windows program and (only a quick look) I don't see that they offer a Mac version. To install a Windows program on a Mac you would first need to buy and install a copy of Windows (e.g. Windows 8). You would install Windows via Bootcamp Boot Camp 5.1: Frequently asked questions - Apple Support or via 3rd party software such as http://www.parallels.com/products/desktop/