Drag to box-select. Right-click to move/attack.
Click your Command Center to queue WORKERS.
Click a Barracks to queue SOLDIERS.
Hotkeys: B=Build menu, A=Attack-move, S=Stop, H=Hold.
Workers auto-mine if right-clicked on minerals.

BUILD (B) +CC 400 +BARRACKS 150 +TOWER 125 WORKER 50 SOLDIER 75 A-MOVE STOP

PLACE CC 400 PLACE BARRACKS 150 PLACE TOWER 125 CANCEL