Hi im pretty stupid when it comes to maths but i really need help with a couple of formulas.

I need something that will allow me to get all of the points in a straight line in 3d .. i know 2d is y=mx+b but i have no idea what it is in 3d

Also i need help in the point formula for circles in 2d and 3d .. i havnt done anymaths for a few years and i forgot all the stuff i learnt at school . If anybody can explain this in lamen terms or point me to a web page that would be great .

Thanx heaps