Select the problem using the black Problem= slider.
Enter your function on the input bar at the bottom as f(x)=... You can type "Pi" for π, or select it from the α on the far right of the input bar.
For example, if you wanted to make the graph of 3sin(2x-π/2), you would enter f(x)=3 sin(2x-Pi/2) in the input box on the bottom of the page.
Use the pink and blue sliders to help in measuring. The blue slider increments in steps of π/12, the pink one in steps of 1/2.