Copy entire appointment

How can you copy an appointment name and time (6:00 - 9:00) entirely to a different day?

I guess you have your appointment as an event in calendar. You can use shorcuts Ctrl+c and Ctrl+v. Choose event you want to copy, press Ctrl+c and then click on the different day in calendar. Press Ctrl+v.
You can also copy an event from main menu Edit->Copy/Paste.