The following is a webpage that calculates estimated regression coefficients for multiple linear regressions

http://people.hofstra.edu/stefan_Waner/realworld/multlinreg.html.

I would like to add on to the source code, so that I can figure out the standard error for each of the coefficients estimates in the regression. I don't understand the terminology in the source code, so I figured someone here might in order to show me how to calculate the std errors.

I would like to be able to figure this out as soon as possible. Thank you for your help.