I am looking for information about how to run a node on the Lightning Network and start using it? Is there a step-by-step guide available somewhere?
Some information can be found here: https://medium.com/@dougvk/run-your-own-mainnet-lightning-node-2d2eab628a8b
But you should ask yourself first what goals do you want to achieve? Estabilishing LN node is not a "make-me-rich-quickly" investment.
This is a tutorial detailing how to set up and start using c-lightning. It walks you through setting up bitcoind, c-lightning and your first transaction.
Additionally, you can find a link collection with information on Lightning, including several setup guides, at lnroute.com.
If you would like to run a dedicated "always on" node, eg. on a Raspberry Pi, I can recommend my own guide :)
Beginner’s Guide to ️⚡Lightning️⚡ on a Raspberry Pi