create simple project and then go to the project hierarchy fast tab and there you must define sub-project ID format "-#" and then your sub-project will be enabled. For resource assigning in Project first you need to configure the HR module, in that you need to maintain the calendar for those employees and then you need to define the cost of that particular employee (for expense) and for Revenue you need to define the sales price of that particular employee. In the project accounting module you need to mention the calendar in scheduling fast tab and then you need to define WBS, in WBS activity you can be able to assign resources.