How do I find the distance between two points?
You need to provide more context.
But if you are talking about two points in the plane you can use the Pythagoras theorem. d = ( ( x_2 - x_1 )^2 + ( y_2 - y_1 )^2 )^½
If you are talking about two points in a 3 dimensional space you will need a generalization of Pythagoras. d = ( ( x_2 - x_1 )^2 + ( y_2 - y_1)^2 + (z_2 - z_1)^2  )^½