Earning STEEM by joining the P2P network & validating transactions?

Hey guys, I'm new to Steemit and loving the community so far!

I'm curious about the ability to earn STEEM through the P2P network as described on the steem.io homepage. I can't seem to easily find much info on it, and was wondering how one goes about getting started with that. Do you need to have a mining rig like with other crypto-currencies, or is it something that is web/app based that you need to actively participate in? 

Apologies if this has been posted about already, or if I'm just being oblivious and completely missing a link to more info on the subject. 

Thanks in advance!