how to design a low pass filter?

Hello

Can I anyone help me to write the matlab code to design a low pass filter to filter a music (audio signal). The signal is (220500x2) matrix with Fs=22050 and the cut off frequency is 300 Hz.

This is what I have done

[signal,Fs]=audioread('signal.wav'); LP(1:300)=1; LP(LP301:220500)=0; fil_sig=LP.*abs(fft(signal)); ===> this line would give me errore because of the dot multiplication and I think I am missing the filter coefficients.

Thanks in advance

[Md Nurullah]

Hello

Can I anyone help me to write the matlab code to design a low pass filter. fs=40khz, N=1000, f1=1e3, f2=5e3, f3=10e3, fc=7khz, Filtered signal/output will be plot as time domain & freq. domain specturm.

TIA!