The subject says it all Where do i even begin what do i need to know.
Just a lot of questions?
I would start at the light source! 
Are you a maths and physics professor, if not I would search for some more maths and physics. Use google!?
I think it’s a bit too frightening to start with math and physics. I did a google search of “ray tracing tutorial”, and came up with http://www.geocities.com/jamisbuck/raytracing.html . This should provide some introduction to the subject.
Do some searches yourself, and I’m sure you’ll find a lot of material on the subject.
thank you.