The screenshot below explains how to easily add a certain task:

(Using mouse, highlight the time needed for the task and release the button: the new task pop-up windows appears. Just enter the text and, if needed, assign Priority, Category, Completion, Alarms and Re-occurrence, then press OK)

Another way:

Press Add button. In the opened dialog:

To enter a non-timed entry for the day: the process is the same, except you need to check the All day event box.

Exclusive task - enabling this option for the task will ensure that this task's time will not be taken by any other task. If you will try later to add a task with time coinciding with "Exclusive task"- EssentialPIM Pro will not let you do it.

All day event - that is the task that does not have a certain time, rather, it is assigned to the whole day and will appear on top of each day