I just started a new game "Base Defence"
Its still underway
To place a unit click on its icon than click to place. than click on a placed radar to assign the turret to it.
The radar will send the coordinates of the target of the radars choosing and the turrets will fire on it.
Place a radar first because you cannot, at the moment, re assign a turret.
you can also by clicking on it, select a turret and purchase upgrades.
By right clicking on a radar you can manually choose a target -click to fire and right click to cancel
I write this because it can be a little complex and i haven't yet put in a help menu or tutorial
To change the start cash so you can afford many radars look under "newgamebutton-mousebuttondown-script editor". its pretty hard to miss from there.
Download and try it and give me a little feedback