The main KTimetracker window has the following components: menubar, toolbar, searchbar, task/time window and status bar.
The searchbar is a combined field. As long as you do not press Enter, it acts as a filter. Then, only tasks that match your input are shown. As soon as you press Enter, your input is used as a name to create a new task.
Choose Configuration for PDA in the Appearance page of the settings dialog if you have a touchscreen and your screen real estate is precious. It will disable the search bar and every click will pop up a context menu.
The various tasks are displayed in this window, along with the time accumulated for each in the current session and in total. Tasks being timed have a small clock icon next to the session time.
Subtasks can be created for each task. Clicking the plus sign and minus sign in front of the main task toggles the view of its associated subtasks. The total time accrued for a task includes the times for its subtasks, as well as its own accumulated time.