[bssd12000]

If you want 3 spaces between lines go up to the toolbar and look for an icon that has an arrow pointing up and an arrow pointing down and next to it on the right hand side some lines drop it down and choose 3 if you just want double spacing and sometimes an extra line between lines press ctrl and 2 and then hit enter. If you mean an actual visible line, go up to the tool bar and insert line.