Modding and anti-virus

So I just purchased a gaming computer, I'm new to the PC scene so I have a few questions. I plan on playing around with mods, is there a good website or forum where I can learn the basics? And what Anti Virus should I be using as I'm sssuming downloading mods increases the risk of getting a virus?

Modding as in making them, or just using ones that exist?

In either case, modding is very specific to each game. You'll get far more information finding a website dedicated to just that game or something like moddb.com to find mods.

As for an anti-virus, i prefer Microsoft Security Essentials. Lightweight, pretty effective, inobstrusive, and - most importantly - free.

Ok thanks a lot guys, and yeah I'm talking about just using them. So once I download them how do I put them into the game?