Primer - using BEST and Pearson's correlation for MDS.

I am using primer to display community data using MDS. I have the manual and "change in marine communities" that I have been using to guide my analysis. I ran the MDS, then BEST, and then displayed the environmental vectors with Pearson. I need to know the finer details of how BEST and Pearson's (such as the equations) are displayed on the MDS. To my basic understanding BEST is an optimization routine that uses ranks to find the correct factors but how so? and how does Pearson use this information to create vectors?

I am having a hard time finding information on this. I am already using Clarke 1993, and Clarke and Ainsworth 1993 (they talk about Spearman), but I guess I am still having a hard time understanding.

Thank you for taking time.