Cubase has difference toolbars you can use. Witch toolbar you use depends on witch editor window is open. To open click right mouse button for pc and for mac use the menu bar. The different items mean the following. To select a tool hold right mouse button and go to the tool you need.
Arrow tool used for selection, moving and duplicating parts.
Eraser used to erase parts
Match Q used to transport a midi track to an other midi track. Adjust automatically to the tempo of the track where you copy or past to.
Scissors used to split a track on the
Speaker used to pre listen. Go to the part of the track and click, the part will be played at that point.
Pencil used to change the length of the part. Just hold left mouse button and drag. Create a new part by double clicking on empty section of a part.
Mute used to silence a part of a track.
Glue tube used to combine two tracks.
Magnifying glass used to enlarge a part of a track.
Log tool used to apply logical presets directly to a part.
Play parameter tools used to change parameter settings. First one for panning, second one for transpose and the last one for volume.
Selection range tool used to make selections
of the parts.
Groove tool used to apply grooves to
Stretch tool used to stretch and resize parts.
Nudge tool used to to move a event one snap. Hold control to move to the right.
Cross fade tool used for selecting cross fade area.
Paint brush tool used to create several notes at one time.