Hi Allen 

Thanks for reaching out in the Lucidchart Community! You can customize your shapes’ style by selecting them and modifying the settings in the properties bar at the top of the editor. To round the corners of a shape select the shape click the Shape Options icon (the square icon next to the bucket icon) and then toggle the arrows or type a pixel value in the "rounded" box at the bottom.

To make a shape transparent (no fill) select the shape click the Fill Color bucket icon and then select the transparent option (the checkered square) from the color picker.

To learn more please review our Add and customize shapes article from the Lucid Help Center and let me know if you have any further questions!