Rests are considered notes without having pitch.
Rests can be inserted in various ways:
using the rest menu
pressing the rest-button and insert like a note with <enter>
use the shortcut <r> to insert a rest with currently selected duration on the buttonbar
When needed rests can be moved up or downwards to accommodate 2 parts on one staff by using <+> or <->
Multi-rests may be used in single voice scores