How to fit a lorentzian function to this raw data?

My research mentor asked if I could help him curve fit the Lorentzian to some raw data.

Disclaimers: 1) I have no experience with curve fitting. 2) I have no idea what the Lorentzian function is.

My raw data is a matrix of x and y values. When you plot these values, you get a concave down parabola (which is good I guess because that's how the Lorentzian looks). I want to fit the Lorentzian and have it spit out 1 value: the width parameter

So, I found this function/script online: https://www.mathworks.com/matlabcentral/fileexchange/33775-lorentzfit-x-y-varargin

I could copy and paste this into Matlab, good starting point? After this, though, how do I actually input my x and y values into the function? Because the function is LORENZFIT(X,Y). Is X an x-value matrix and Y a y-value matrix?

Thanks so much! Sorry for my complete ignorance on the subject. I tried watching some youtube videos on the Lorentzian function but those really just shed light on the theory behind the function.

[BURCU OZDEN]

A=load('name of the file where your data is.txt');

>> x=A(:,1);

>> y=A(:,2);

[Bjorn Gustavsson]

You'll find information about the Lorenz-profile here:

google: lorentz-profile