Open 
a file or create 
a new record.
Move the left selector 
to the desired start position.
Move the right selector to the desired end position.
Press Play 
and Stop 
. Tap on Zoom in 
to preview and adjust your selection.
Press Zoom in to adjust your selection more precise.
Now you can apply to the effects, mix import, cut, copy, insert silence and delete to the selected area.