Are there any shortcuts for the my command?

No, this command does not have any aliases or shortcuts.

What rank do I need to use the my command?

You need the Admin rank or higher in HD Admin to use this command.

Type ;my [Message] in the chat while playing a game with HD Admin installed.

No, this command only works in games that have the HD Admin plugin installed by the game developer.

HD Admin Admin

The my command sends the specified message to everyone on the game in yellow text.

This command sends the specified message to everyone on the game in yellow text.

;my [Message]

Example: ;my hello!

This command sends the specified message to everyone on the game in yellow text. Run this command from the in-game chat by typing ;my.