A custom job consists of tasks. Task involves its own duration in hours and rate per working hour.
To add a task to a custom job:
Description: enter the essence of the task.
Rate: enter the fee for this task per hour.
Time: enter time in hours necessary to complete this task.
Note: optionally, enter note about this task.
Mind that tasks as well as custom jobs will appear in the user control panel. This way your customers can see what should be or has been done.