You mean something like this:
A vector in cod is (x,y,z) = (forward, left/right, up). The most used function with vectors in cod are distance, VectorNormalize and VectorToAngles.
With distance you can calcatulate the distance between two points.
Example:
Code:
one = (0,0,0);
two = (100, 0, 100);
dist = Distance( one, two );
With VectorNormalize you get a vector between 0 and 1. So (0-1, 0-1, 0-1).
Example:
Code:
difference = VectorNormalize( end - start );
With VectorToAngles you can calculate the angles you need to get from your current position (vector) to a other position.
Example:
Code:
angles = VectorToAngles( end - start );