Hi @atalay251, I moved your post into this thread. You can take a look at the Mobile Quick Hookup section to see if there are other players with a server to join.Is there a way to join a multiplayer online server?
Otherwise to join a multiplayer online server, either your friend would need to set one up and give you the details, or you woukd need to set one up using the guidelines here: Terraria Mobile 1.3 Multiplayer Setup Guide