Lumos can be like using a light only wider range of light and a slight blue glow.
Accio can be like reverse hookshot except it wont work on walls or bricks.(maybe on bricks if it fakekills then brings the killed brick to you)
Advada Kedavera can shoot green projectile that is one hit kill.
Stupefy can make you tumble
nox turns off lumos
EDIT:if its gonna have a GUI make each spell have a diferent button to do each spell and when you click the button it will prform the spell<obiously> but also make you character automaticly say the spell like if you press the lumos button then it will make your blockhead say Lumos! then make a light around you.