To open a new tab go to the file menu -> new tab or press control shift t with the button that looks like a +. To close a tab press the X button near the right hand side of the tab.
To launch qterminal in a normal window go to the menu -> System Tools -> qterminal or run qterminal from the command line. To launch a drop down version of Qterminal from the menu -> System Tools -> qterminal drop down or run qterminal -d from the command line.