You can find the Blank Diagram template by searching for "Blank" under New Document on the dashboard.
Click on Blank Diagram from the search results.
The blank diagram is unique among SmartDraw's offering. It has no diagram specific presets.
Even without any specific diagram presets, it still has a basic SmartPanel docked to the left of your work area.
Here, you'll have access to a basic set of symbols like rectangles used to make common process related diagrams.
To add a shape, simply drag it from one of the docked libraries or search for a symbol.
Move your cursor over one of the yellow circles and you'll see it turn into a pencil. You can now draw a line connected from that shape to any distance and direction. When you let go of the mouse, you'll see a pop up of common shapes you can choose to attach to the end of your line.