Open the chat
Type `/tp yourname targetplayername`
Press Enter
If cheats are enabled, use `/tp @s targetplayername`
If you want to teleport to specific coordinates near them, use `/tp yourname x y z`
In Java Edition, you can also use `/tp yourname targetplayername`
In Bedrock Edition, use `/tp yourname targetplayername`
If you do not know the exact player name, use tab completion if available