Howto sketch a graph of y=2sin3x-1 for 0<=x<=360.
Just draw a normal sine wave
Now label the y-axis so that the amplitude is 2, rather than 1.
Now shift the x-axis up by 1, so the curve oscillates between -3 and 1, rather than -2 and 2.
Finally, label the x-axis so the period is 2pi/3, rather than 2pi.