Before you can paste time into a track you must have time in the clipboard to paste. After selecting a block of time, you place it into the clipboard by using either Cut Time or Copy Time.
Cut Time
Deletes the selected block of time and places it on the clipboard.
Copy Time
Leaves the selected block of time unchanged and places a copy of it in the clipboard.
Cut Time: Deletes the selected block of time and places it in the clipboard.
The block of time is deleted from the selected tracks and stored in the time clipboard. Keys to the right of the cut block slide left to fill the deleted time.