Vector drawing is made up of points and lines connecting those points. You can always later change the size of what you've drawn, as well as the fill/stroke/filters.
Any shape you draw, the Properties bar shows you the options in sections.
In the Fill section, you can fill shapes with the following types of fills:
Once you select the type of gradient you want...then you can set the colors by clicking on the little squares at the bottom.
Once you've set the gradient, you will see handles on the shape. You must have the shape selected with the black arrow in order to see the gradient handles. To change the direction to top-to-bottom,
To add Filters, do NOT go up to the Filters menu at the top!
Click on your layer/shape with the black arrow tool and go to Properties bar at the bottom and click on the '+' button.
You see options like this...