Curves are created by adding an anchor point where the curve needs to change direction, and dragging the direction lines that will shape your curve. The heights and angle of the lines will determine the shape of your curve.

Blending mode controls how the layer interacts with other layers. For example, the blending mode "multiply" looks at the color of your layer and multiplies the base color by the blend color. The result is always a darker color. Multiplying with black results in black, multiplying with white leaves the color unchanged.