Install Java
Download the Minecraft server .jar file from the official Minecraft website
Create a new folder for the server files
Move the server .jar file into the folder
Open a terminal or command prompt in that folder
Run the server .jar file to generate the initial files
Open the eula.txt file
Change eula=false to eula=true
Save the eula.txt file
Run the server .jar file again
Edit server.properties to configure the server
Open port 25565 on your router and firewall
Find your local IP address
Share your public IP address with players
Keep the server running while people play