To use the copy and paste functions you just hit the button to the right of the title bar for Lector. Then a menu will appear with the cut, copy and paste options.
The button to the left of Lector is to switch to a second page.
In the app you want to paste to, you must show the tools by pressing the camera button. Then you should be able to paste using the paste bottle icon.
Let me know if you have any other questions.
Chris De Herrera