Make a diving board in a partstudio, or include the base with an assembly (sample document here).
In a new Simscale project, import a geometry from your Onshape library then create a Static simulation
Choose a material for your diving board, then add a fixed support on one of the sides and a force on the top face.
You can click on displacement to see vectors, and displacement in the Z axis to view the magnitude of the bending.