Bit of a genralazation there. Since the Data model comes first here is a link to tons of data models there is like one that you will be able to use. Data models
If you have specific questions let us know and we will help out.
Why not have a table with number of hours with an ID
Shift table - employeeID, HoursID, Start Time, Date
Query - employeeID, HoursID, Start time, EndTime:[StartTime]+HoursID using DateDiff