Hello Shirley,

 If you haven't seen the help video about adding features, you might want to take a look at http://mylandplan.org/video/add-features-and-points-interest

When you are drawing a line, if you double click the map it will complete the drawing of the line with an endpoint. Once you finish a line, the only way to add a new point is to click and drag a midpoint. These points are a lighter shade then the points you put on the map. When you drag a midpoint, you will get a new point that you can manipulate. You cannot add a new endpoint to a line. You can only drag enpoints to a new location. Ideally, you would want to draw the entire line all at once even if they points are exactly where you want. Then you can click and drag points to move them if they aren't exactly where you want them. Hope this helps.