Finding the difference equation given the impluse response

[lusher00]

This question is for a DSP class. I hope that I am posting somewhere appropriate.

So given the impulse response:

h[n]=((0.5)^n-(0.25)^n)u[n]

find y[n].

Where do I start? I don't need an answer, just a nudge in the right direction.

 

[CEL]

In order to obtain the output, you need the input waveform and the initial conditions. What are they?