Security is often overlooked for wireless networks.
What can happen without good security? You leave yourself open to hacking. Other people may have access to your financial information and other personal files.
This can be prevented by setting up good security. Early security was something called WEP. If this is what you have, it can be hacked in about half an hour if you are active on your network.
You should set up WPA2 if possible. Sometimes older wireless notebooks do not support better security. I suggest getting a USB wireless adapter and upgrading.
Get someone to set up security if you don’t know how to do it yourself. You can set up your system with WPA2 so that it is very secure.