Depending on your background, you might want to take a look at something like the Cisco CCNA material that covers basic setup, operation and networking. It's a great primer and there are plenty of free resources available. Here are some popular learning resources.

Router Sims like - https://www.boson.com/netsim-cisco-network-simulator

Book - https://www.amazon.com/Routing-Switching-Complete-Study-Guid...