Once you've set it up, give your friends your IP address, and they'll be able to join. There's a few different ways to set up port forwarding, and instructions you'll need specific to your router can be found here. You'll have to set up port forwarding to open up your Minecraft server to users outside your local network. However, right now your server is only accessible to devices using the same internet connection as you. Technically, your server is ready to fire up now, and you'll also see a few new files in your server folder, including the 'server.properties' file where you can customize your game. Be patient, as depending on your computer, creating your server may take several minutes.