This is very simple.

• Get the monero-cli binaries.
• Unzip and go inside the directory before opening a terminal session.
• ./monerod --rpc-bind-ip 127.0.0.1 --data-dir /directory/you/choose.

This will run a monero node, the RPC will be accessible on 127.0.0.1:18081 and the blockchain location where you specified before.

If you want to make the RPC accessible from outside your local network, follow this tutorial