To create the text field in which the to-do items are typed, you need to add a Text part and a Label part:
The information area at the bottom of the Composition Editor displays Category: Data Entry Part: Text, reflecting the current selection in the parts palette.
If you accidentally picked the wrong part, select the correct part or
select the Selection tool
from the tool bar to unload the mouse pointer.
After you have added the part inside the window, you can move it to a new location by dragging it with the mouse.
When initially placing parts, don't worry about the exact position of the parts for now. Later you'll learn how to use the tools from the toolbar to match sizes and align parts.