How can I select a piece of text and cut, copy or paste it?

On the text that you want to select do a long press, this will highlight the text and two brackets will appear at the start and end of the highlighted text. By moving the brackets you can highlight more or less of the text. When the text is highlited contextual buttons will appear in order to cut or copy the text. In order to paste the text choose the position where you want it placed long press and a contextual paste button will appear.