Here are the different steps you need to follow to customize the color of a shape.
1 - Go to the outboard bar, then click on "Add", then "Shapes".
2 - Choose the shape of your choice and draw it on your Board
3 - Choose the colors of the shape as well as its outline
By clicking on the pointer (at the bottom right of your toolbar), click on your shape, then you can change the color of its outline as well as its color.