You are obviously a noob. But unlike haters who critisize, I will help you. First of all, ctrl is very helpful. Hold it down and drag to create a square/rectangle. Next you can create a line by holding down shift and dragging. You can increase the size of the line by just scrolling up. Next, if you press tab, you toggle between circle, triangle and square. Those are the basic controls. Good luck with your next save! :)