I need help with a 3D game I wanted to make and I don't even know how to make a 3D game.
Construct 3 is mainly a 2D Engine.
If you dont know how to make 2D in construct 3, i would not advise you to start making 3D in it.
Try some 2D Projects first, then you can start using 3dshape, 3dobject plugin etc in c3.