A squad is on the way to attack my colony. How do I defend it?

i'm not quite sure of this, because i haven't actualy played yet, i can't get the client working

but shouldn't your colony be defended if you have troops in it?

Go to "Orders" in the upper left pannel,sellect "Main Base" click on the arrow facing up ("Recruit") and if you have enough metal and/or oil you should build the units you want or have tech for...to build the same unit again click on the image of the unit with a plus on it(near the arrow facing up)

also a TIP

if you have basic scanings you should do an incomming scan