Press and hold [ Spacebar ] to pause the game and open the Tactics HUD. Along three sides of the Tactics HUD overlay are tabs with icons representing the actions your squad can take.
Clicking the weapon icons changes the firearms used by each squad member; there are also hotkeys available. Pistols [ F1 ] and Shotguns [ F2 ] are handy at short range. Assault Rifles [ F3 ] excel at medium range. Sniper Rifles [ F4 ] dominate at long range. You can also cycle through Shepard's weapons outside the Tactics HUD by using [ ] ].
Each character can equip all four weapon types, but not all characters are TRAINED to use each weapon. If you order a squad member to use a weapon they are not trained in, their accuracy and damage will suffer.
Clicking on Power icons orders the use of a combat Power. Powers range from Kaidan' biotic abilities, to Ashley's combat techniques, to Tali's engineering skills. Moving the mouse cursor over a Power's icon will describe its effects.
At the top of the two squad member's menus are four additional buttons that allow you to issue squad commands to them. These commands can also be issued outside the Tactics HUD by using hotlkeys.
Move (hotkey [ Up Arrow ]) - Move to the location under your targeting reticle.
Hold Position (hotkey [ Right Arrow ]) - Hold current position.
Attack (hotkey [ Left Arrow ]) - Attack the enemy under your targeting reticle.
Rally (hotkey [ Down Arrow ]) - Return to Shepard's side.
At the top of the Tactics HUD are Shepard's Power hotkey Quick Slots. As Shepard levels up, you gain new combat Powers. To add new Power to your Quick Slots, click and drag any Power icon from Shepard's tab to a Quick Slot.
You cannot utilize your squad member's powers using the Quick Slots.