routers sold these days are wireless even if you aren't using them wirelessly) and you just plugged it in and started using it then 99% likely you are not safe.

Your home or office wireless network should always have "encryption" turned on, which is like a home security system that only gives access to someone with the right password. They're not impossible to break into, but they make it too hard for most people.

If you use your laptop in a public network like at an internet cafe or other public wireless hotspot (whether or not you have to pay to use it), you run many of the same risks, especially if you don't have a firewall turned on, aren't using good enough (or any) antivirus software, and more.

Understanding all the important factors in protecting your computer's security is absolutely critical these days. Most people using computers are in danger without even knowing it. Make sure to educate yourself and keep yourself safe.