RE: What is a Steemit Witness and How do I get one?

42 is your reputation score.

I'm a witness, former top 20. Currently 32 I believe.
Your vote for witness coupled with your SP helps move the witnesses up or down the list that you like or see doing good for the network, and has good uptime for blocks, is fast to update or fix falled servers, and ultimately are working for the network. If you're a witness the network pays you for securing and building the network. The miner explanation is close to true.. In this case the community vote decides who creates the networks blocks.