It's a SCAM, the owner is a Jewish Mexican who calls his name under the title of DR.. I assure you he never ended a masters degree, just another trick to make people fall in his game. PLEASE DO NOT FALL FOR THESE KIND OF FAKE INSTITUTIONS, cheap things cost more at the end.
Take your time and go to a real University or go online and look for accredited ones (Phoenix, Thunderbird, etc).
ALOHA

This depends on the code for your area, start there first. It will also depend in the angle of the stringer. If you are using a 2X12, you should work to a 9 to 9 1/2" stringer tread depth and then a stair tread with a 3/4 to 1" nose extension on top. That will give you a 10" +/- surface, a comfortable step. Less than that you need to "tippy-toe" since a normal size 10 shoe is about 12"..