I have not secured my wifi connection at home. Is it risky? If I need to secure it are there easy to follow instructions some where? if some thing goes wrong can I easily reset it? I am using LinkSys router.
It's risky for a number of reasons, including:
...and many other reasons.
To secure it, simply set up a password and an encryption scheme (avoid WPA and WEP, they are easily cracked). I'd recommend using WPA2. Since the router is in your posession, you can easily hit the reset switch at any time (a small button usually located on the back or bottom of the appliance). Keep in mind resetting the hardware will usually erase your configuration, so I'd back that up once you're comfortable with it.
The reasons John T gave are good reasons to secure you router. It does depend on where you live, though. If you live in a semi-rural area you will have few neighbours that have the ability to even detect your wireless network.
Still, it is simple to secure the network, costs you nothing, and you'll learn something new!
You can find several videos on YouTube where people actually talk you through the process. Here's one to get your started (and the related videos on the side will point you to others): http://www.youtube.com/watch?v=DhNAsnqnHWc
I wasn't a big fan - I thought he was using much too technical language for his target audience, but he gets it going.
You should always secure your wireless for a great many reasons. "John T" already posted a great list, unfortunately often people still feel that these are the type of things that would never happen to them.
Sometimes real world examples work best and here are two stories about people who probably didn't think it would happen to them either:
Both articles relate stories of innocent people who were investigated for participating in child pornography. In both cases, it was someone nearby connected to their unsecured WiFi that was found to be committing the illegal activity.