Wiffleball riser?

i am having trouble throwing a riser with a wiffleball i have looked at pretty much all the websites and videos but none really help me out i dont know if its my grip or how i release it but i normally grip it holes facing down (im a righty) with middle finger on the seam and index finger 2 inches away with thumb on bottom of the ball i heard u should release it sidearm towards the ground but i just cant get it right can anyone help me?