Can Matlab code give me a solution to find frequency from its difference equation?

Hello, I am trying to find a solution and then frequency from the following difference equation: 8*y(n) - 6*y(n-1) + 2*y(n-2) = 1 with n>= 0 and initial conditions: y(0) = 0 and y(-1) =2. After I found its Z-transform function as H(z) = (z^2 - 4*z)/(8*z^2 - 6*z + 2), I stuck here. Can someone give me some suggestion? Thank you! I am new to Matlab, how do I accept your answer?

[Nirja Mehta]

Try out suggestions here