Make sure everyone has Minecraft Java Edition
Make sure everyone is using the same Minecraft version
Add each other as friends on the Minecraft Launcher or Microsoft account if needed
Choose a way to play together:
Open to LAN for players on the same network
Create a private server for online play
Use a hosted server service
Use Minecraft Realms for an easy private world
If using LAN:
Open your single-player world
Press Esc
Click Open to LAN
Choose settings and start the LAN world
Have friends join from the Multiplayer menu on the same Wi-Fi or network
If using a server:
Get the server address or IP
Open Minecraft Java Edition
Click Multiplayer
Click Add Server or Direct Connect
Enter the server address
Join the server
If using Realms:
Subscribe to a Realm
Open Minecraft
Go to Minecraft Realms
Invite your friends
Have them accept the invite and join
Make sure everyone has a stable internet connection
Check that firewalls or antivirus software are not blocking Minecraft
Use the same mods or resource packs if the server requires them
Keep voice chat or messaging open if you want to coordinate while playing