Third Order Low pass filter question problem

Hello Guys i am having a real problem with the third order Low pass filter, i have done the first order LPF but i can't start using the third order lpf I wonder if you can help me out on how to start out i want to get these:

For all the filters in this assignment use the Matlab to generate the following plots:

1. Pole-zero plot and the unit circle in the Z ́domain.

2. Magnitude response of the filter in dB in the frequency range p ́π ă ω ď πq.

3. Magnitude response of the filter in dB in the frequency range p ́ωp ď ω ď ωpq. Use this plot to get

an approximate value of the passband ripples.

4. Phase response of the filter in the frequency range p ́π ă ω ď πq.

5. Group delay of the filter in the frequency range p ́π ă ω ď πq.

6. The filter’s impulse response.

if some one can help me out with the first step i can move on to the second