<<< What hardware do I need to add to the Wired Network for the Laptop to be connected as wireless connection >>>
Assuming that the laptop has wireless capability built-in, then you only need a "Wireless Access Point" which can be plugged into a spare LAN port in your router. However, stand-alone Wireless Access Points tend to be very expensive compared to Wireless Routers (which incorporate a Wireless Access Point). It might be no more expensive to buy a Wireless Router and replace your existing one.
<<< I wish to make the Wireless connection safe. What do I need to do this >>>
The Wireless Access Point will have the facility for securing your wireless connection - WEP or WPA encryption and MAC address filtering.
MAC address filtering allows you to enter the MAC address of those wireless adapters that are allowed to connect to the Wireless Access Point, other adapters will be blocked.