how to understand generalized linear regression result

After using mdl=fitglm() to create generalized linear regression model, the matlab displays the regression results. How to understand "Dispersion", "Chi^2-statistic vs. constant model", and "p-value"? The good model needs bigger Chi^s value or smaller one? And also p-value and dispersion?

Thank you for any answer.

[the cyclist]

What you are asking for is a tutorial in basic statistics and mathematical model. I don't think this is the best place to find that.