Bring up the Tables and Borders toolbar (View > Toolbars). Place your cursor
in the cell you want to split and click on the Split Cell button. This will
divide the cell with a vertical line into two cells.
Thanks I meant to split it so the 2 cells were stacked on top of each other -
the quick way (which took me a while) is to enter the text on 2 lines then
insert a line between the two halves.
What you are trying to do is plit the cell horizaontally. To achieve this,
do as I noted in my earlier post, split each cell again. You will now have
four cells. Now, select the top two cells and click the Merge Cell icon. Do
the same for the bottom two cells. This should provide what you are actually
looking for.