Put your mouse cursor over the beginning word of the phrase.
Press the left mouse button; with the button pressed, move the cursor to highlight the phrase.
After the phrase has been selected, press [Control][C] -- (this puts the phrase into short term computer memory, Copy)
Begin your reply
Use your preferred method to highlight the phrase, to show your are quoting. I use italics and quote marks.
Put your cursor where you want the phrase and press [Control][V] (Paste)
The phrase should appear. Close the italics and close the quote, then write your own response.
Any use of H T M L coding requires a break < br > or paragraph code to move to the next line < p >
That's how you cut and paste.
Unless you're on an Android tablet, but we'll save that for another day. Is that how it works on a Mac?