Simple 2.4ghz Collinear Antenna How Do I Check What Devices Are Using My Wireless Network?

How do i check what devices are using my wireless network? - simple 2.4ghz collinear antenna

I have a wireless router and just want to make sure that my neighbors in my Arent connection. I have the network key, angry, but until my father for me to do so. Is there an easy way to check which devices are using my wireless connection? I have DSL if that matters. and use a Linksys Wireless Broadband Router 2.4GHz.