Applying a multistage filter to a signal, how?

Dear Readers

Considering the filter explained in the mathworks documentation centre:

Fpass = 0.11; Fstop = 0.12; Apass = 0.02; % 0.02 dB peak-to-peak ripple Astop = 60; % 60 dB minimum attenuation M = 8; % Decimation factor of 8 Hfd = fdesign.decimator(M,'lowpass',Fpass,Fstop,Apass,Astop);

Hm_multi = design(Hfd,'multistage')

Hm_multi =

     FilterStructure: Cascade
            Stage(1): Direct-Form FIR Polyphase Decimator
            Stage(2): Direct-Form FIR Polyphase Decimator
            Stage(3): Direct-Form FIR Polyphase Decimator
    PersistentMemory: false

If my original signal supposedly sampled at 8KHz (want to dowsample it to 1KHz, thus M=8) how do apply the Hm_filter to the data for decimation. Apply the filter first and then decimate the filter output by 8? I note that the filter has three stages that would suggest applying it in a multi-stage manner. Thanks in advance! Para