So, My Laptop Has WIFI Capability - Why Aren't I Internetting for Free Then?

I've got this laptop and it connects to my isp or Internet Service Provider's wireless router via the WIFI ON button. Now, this means my humble laptop's wireless broadcast is strong enough to (not only receive hi-def files but also) SEND material to this device through the air.
If my humble laptop can broadcast through the air, why am I still connecting to the internet via my ISP, i.e. paying for their broadcast distribution service?
In fact, wasn't this how the internet was SUPPOSED TO WORK in the event of Nuclear Holocaust, where peer to peer nodes share information in encrypted packet fashion and get decrypted at user end?
I'm (obviously) not the most technical of bloggers, but I'd be interested to hear from coders who've converted their WIFI-ON laptops into self-standing or peer-to-peer internet-connection nodes, and what results they're getting (obviously it'll depend on who you're near). What's the range of laptop wifi hardware? Can it be enhanced/tuned such that it's more of a beam on a signal? I'm asking too many questions, gimme answers.
If there's software out there, to convert my laptop to a FIM or Free Internet Machine, I'd use it. What's the alternative?