To select text, double-tap a paragraph.
A pair of pins will appear; the one with the blue ball on top is the starting selection point and the one with the blue ball on the bottom is the ending selection point.
Drag one or both pins to select the text you need. When the text has been selected, the Cut / Copy / Paste menu will be displayed.
To delete the selected text, touch the Backspace key. To paste the selected text, double-tap the target point of the script to bring up the Cut / Copy / Paste menu and touch Paste.