Complex sentence: You can leave an indented reply to someone else's message by beginning a line with one or more colons, and be sure to sign your messages with four tildes (~ ~ ~ ~) to mark it with your username and a timestamp.
Split into simpler sentences: You can leave an indented reply to someone else's message by beginning a line with one or more colons. Be sure to sign your messages with four tildes (~ ~ ~ ~) to mark it with your username and a timestamp.