Ok; you'll need at least three tables:

Employees
 EmployeeID
 LastName
 FirstName
 <other bio data>

Tasks
 TaskID
 TaskDescription

Activities
 EmployeeID   << link to Employees, who's doing a task
 TaskID       << link to Tasks, what they were doing
 StartTime    << date & time activity started
 EndTime      << date & time the stopped

You can create Reports grouping by any timespan you wish, and use the
DateDiff() function to calculate how many hours were spent on each
task.

                 John W. Vinson[MVP]