2 Waves on a string help needed

[jimmy_neutron]

This graph shows a snapshot of two waves on a string moving towards each other at time t = 0 sec. The pulse on the left has a velocity of +1.0 m/s and the pulse on the right has a velocity of -1.0 m/s. The horizontal axis is the position down the length of the string measured in meters and the vertical axis shows the displacement of the wave in centimeters. Draw graphs of the waves at t = 4 s, t = 5 s, t = 6 s and t = 10 s.
http://i51.photobucket.com/albums/f382/physicshelp/untitled.jpg

I know that the superposition principle probably comes into play here, but can someone help me with how I am supposed to draw the waves when they come together. Thanks.

[maverick280857]

Well its simple if you draw several diagrams showing how the two pulses combine. You need to work out the time at which they meet each other and what the displacement of that point is. Its a simple vector addition of displacements. Try it out.