PEN TOOL

 Closed Geometric Rectangle: 

To create this closed geometric rectangle I had to use straight lines and connect them. I did this by using the pen tool and simply dragging my line across to get the length I wanted. I did the same for all four lines. 

 Closed Curved organic Shape: 

To create these curved lines I had to first create a straight line and then clicking it to drag it until I gave it a diameter, creating a curve. I did the same along my lines until I finally connected them.

 Curved Arrow at the End and Curved Arrow at the Start: 

After you create a line, either straight or curved, you can add an arrow to either it's end or it's start (or both). To add an arrow, you have to open the STROKE window. Once you are in there, open up

Your OPTIONS.  There you should see the options of "arrowhead".

The options to your left are the arrowheads for the start of your line. And the options on your left are the arrowheads for your ends.         

Different Stroke:

With the STROKE window still opened, you can change the weight of your line, meaning that you can make it thicker. The higher the weight, the thicker the lines appears. You can also make your lines into dashed lines. This is done by simply selecting the "Dashed line" key box.