Parks - Mcclellan passband linear FIR filter design

Hello, i want to design this Parks - Mcclellan passband filter with this specific characteristics: passband cutoff=[2 20], stop band cutoff=[1 21] and passband/stopband ripple=0.3/30, but i am not able to find any example concerning the passband Parks-Mcclellan filters. Even in the Matlab help there are no figures which illustrate the result for the implementation. Please help me.