how to draw a circle in Photoshop?
Using the Ellipse Tool (for perfect circles):
Select the Ellipse Tool from the toolbar on the left side. It looks like a perfect circle or an oval depending on the version of Photoshop you're using. (You might need to hold down the Rectangle Tool to reveal hidden shape tools and find the Ellipse Tool.)
Hold down the Shift key on your keyboard. This will constrain the shape to a perfect circle as you draw.
Click and drag your mouse to draw the circle on your canvas. The starting position determines the center of the circle, and the distance you drag determines the radius.
Release the mouse button when the circle reaches the desired size.