To copy rows, you have to select them first.

There are 2 ways to select them:

• click on the row indicator  (1)
• right click on any cell of the row (2) and choose the option "select row" (3)

Even multiple rows can be selected.(4).

 To copy the selected rows, you have to press Ctrl+C.

You can paste rows by pressing Ctrl +M and then Ctrl + V.

After pressing Ctrl + V, you will see import preview.

If there is any problem with the import, you the problematic cells red (1). 

If you hoover on the red cells, there will be an error msg of it, so you will be able to see the problem (2).

If you fix the problems, you will see the preview without any red cells and you can click on "Create" (1).