Many months ago we had a tutorial on the forum about cut and paste. I couldn't do it at the time and was very grateful for the lesson and being able to practise on the thread.
Here's the sequence - if I've got it wrong someone please correct me.
Left click at start of text to be copied, hold down and run over text. Check that all area to be copied has turned blue.
Right click, and left click on 'copy' option.
In the 'Reply' box you may paste the copied material at any point.
Left click to position cursor and then right click and select 'paste' by left-clicking - the selected text should appear.
If you practise on this thread I'm sure you will soon master it.