[The Weed]

You need to be in Shuffle Mode.

If you want to copy a definite length and insert that same length at a definite spot, in Shuffle Mode, Shift+Click on Grid Mode.

Either way, in Shuffle Mode, highlight the area you want to copy, copy, put the cursor where you want to start inserting the copied audio and paste.

Slip (or Grid) will place the copied audio over whatever is there when you paste. At the insertion point, Shuffle will insert what you've copied and move everything to the right of the insertion point, to the right.

If there is something farther to the right on the Timeline you don't want moved, Lock the first Clip of what you don't want moved and that Clip and anything to the right of it will stay in place.