timing belt and pulley

[reefy86]

been searching since yesturday to try and find an awnser for my question but cant seem to find one, im following a design ive seen regarding the z axis and i like how he has hidden his z axis motor rather then have it sticking up in the air but he uses pulleys with a 10mm pitch and im just trying to find out how to work out how wide you need the belt and pulleys, what ratio, how many teeth and the difference between 5mm pitch and 10mm pitch.

also how would i go about fitting a pulley onto this nema 34 motor?

cheers

Ash