|Adding wireless to an existing network isn't that complex a task. |
Without knowing how your existing network is setup, what hardware you're using, what kind of wireless you wish to provide, what you have for budget for this project, and finally, what level of equipment you wish to use it's hard to give you any solid advice so I'm going to keep it simple.
If you're using SOHO level equipment and you already have your internet connected to a SOHO Router that isn't wireless capable, the simplest thing is to buy a wireless access point (AP) and add it to your network. Alternatively, you could buy a wireless SOHO Router and add it to your network. Once added, you would configure your wireless network on it.
For info on adding a second router, simply click on my name above in this response and read my “how-to” guide titled, “Add a second Router to your LAN”
You'll want the single subnet scenario where you interconnect the switches LAN port to LAN port.
Where wireless is concerned, security is an issue you want to keep solidly in your mind. If you want wireless clients to have access to your internal network you will want to encrypt it with WPA2 and use a complex key.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.