Looking how to create a personalized formula in excel 2010?

I have a spreadsheet with the records of at least 80 employees from which I need to calculate their daily and weekly weighted time performance I do this manually by adding the sum of hours that the employee worked during the day and the week, then to obtain the time percentage of each work order that the associate worked on i divided the total amount of time that the employee worked in all of the work orders by the amount of time worked in every single work order, and then I format the number as a percentage, I tried to use the MAX function in excel to identify the maximum amount of time and divided every single record of the employee but my problem is that when I created a formula personalized formula I can not apply it automatically because I do not know the instruction to show excel how to recognize where to start applying the formula for each employee, if some one can help me I will be more than happy to provide a file with a more clear sample of what I need