In the BibleReader, you can add Personal Notes to specific verses in the Bible text. Notes can only be added to the active verse on the screen, which is the verse that shows at the top of the window. You can also see what verse is active by looking at the top toolbar - the active verse will be listed here:
To add a note to the active verse, just go to Menu > Tools > Notes. Type in your note, then select Save to save your changes. To view notes you have written, just open the note edit screen again via the menu, with the active verse one that you have made a note on.