Assuming you have DSL or ADSL connection, an integrated modem/router with wireless (if Tata haven't already supplied one). Look at Linksys, Netgear, D-Link products.
And (if your laptop doesn't already have one) a wireless adapter for each computer. PCI or USB type connector for desktop, USB or PCMCIA type connector for laptop. Again look at the brand names mentioned above.
The manual for the router should tell you what to do.