Assignment Budget Values and Position FTE/Headcount

Could anyone provide assistance on what values are expected on the Position>Hiring Information and Assignment>Others>Budget Values areas in relation to FTEs and Headcounts? We want to use shared positions for our summer hourly staff and are unsure of the values that are expected in these areas so that HR staff do not go over the set limit for the position. For example, if the Headcount for a position is set at 50 and the desire is to allow 50 employees to work 19 hrs per week each in this position, what values should we put in the Position fields and