I live in an area thatI can see a number of differnet WI-FI SSID names available.I am concerned that people are using my WI-FI signal even though they don't know my password. Is there some way to help protect me from this?
Yes. short answer Hidden SSID. Almost all Wi-Fi routers provide the ability to "hide" the SSID which is the technical name for the network name. It stands for the Service Set IDentifier.
Now there is an argument that hiding the SSID is not adding any security. Because there are utilities available that can find hidden SSID's. Well I will argue that if if it is hidden 99% of the people will not try to find it. The 1% will. I will say 99% is better.
So when you are setting up your network name chose to HIDE it. Also add a secure password. Now when you initially want to connect to the SSID you must Manually type the name (yes it is case sensitive.). On a PC click add network name and type it in. On an iPhone chose "other" and type it in. On a Mac "join another Network". and an Android Add WIFI, then the name.
You will likely also need to specify the type of password security which is normally WPA2. This is identified when you enter the name and password to your router. Of course if you are like Ken and use your CAT's name for a password, don't also use the CAT's name for the hidden SSID. Actually Ken has very long and secure passwords.
I am paranoid about security so consider adding another layer to your WIFI network. Something else to consider. Use a Guest level WIFI access so your guests can connect but can only access the internet. Your regular (non-guest) WIFI network access can allow you to access any other devices on the network.