There are a few options you have. First you need to make sure the lines or groups of lines that you intend to connect are combined. So you need to select them all and combine them or Ctrl + L. Then, when you have the shape tool selected, in your top toolbar once you have selected your nodes, there is "join nodes" command which essentially pulls the nodes you have selected together, or the "close curve" command which creates a new line segment in between the two nodes you have selected. Like J hill pointed out, these commands are also available when you right click. If you have multiple broken points, the only thing you have to keep in mind is you have to do this two nodes at a time. You cannot always select all nodes and use "close curve" and expect it to know what node needs to connect to what node. Also as long as all of those lines are combined first, you can click and drag a node with your mouse and snap it to the node you want to connect it to and that will close the curve as well.