Hi Tracy,
This lines indicate what alignment the text will be in. Let me explain: If you move the cursor around the page, towards the centre of the page (horizontally) the lines will appear underneath the cursor. If you double left-click then you will be able to type where the cursor is placed - the text will be aligned centre. If you do the same to the right of the page then the text will be aligned to the right margin. The little lines next to your cursor just show you what alignment the text will be if you double clicked in that particular place. If you look at the little lines they actually mimic the icons on your toolbar for left, centre, right alignments. You can even create an indented line by double clicking about 1 inch in from the left margin - see the little lines change to have a tiny arrow on the first line, indicating an indent!
Hope this helps?
Paul.