Mouse control

Hi. I downloaded Darwinia today. I was just wondering about how you fire your weapons when controlling squads. I've been told that clicking moves the squad while shift + click fires their lasers. The problem is that after getting grenades I can't get my squads to just fire their lasers. What are the separate commands for primary and secondary weapons?

Now, I know how the controls work with a two-button mouse, but I just have the one button.

Hold down the left mouse button and it should fire.