after loading vector art into mach3 where do i go from there?
You don't load vector art into Mach 3. Mach 3 takes a file of g-code and interprets that file into electronic pulses to control the stepper motors (typically). A g-code file is a text file in format that tells the machine to move to a given coordinate, then move here, then turn on the spindle, then move there, etc.
It is possible to write the g-code yourself after studying the individual command and trying a few things, and for simple patterns, many CNCers' do just this. However, soon you will want make more complicated shapes and designs, and writing g-code quickly gets unacceptably tedious and error-prone.
You then need an intermediate piece of software to convert the vector drawing into a g-code file. This is sometimes referred to as the CAM software (which is Computer Aided Manufacturing, as distinct from Computer Aided Drawing, or CAD) Sometimes the CAD and CAM are in one package. Mach comes with Lazycam, a freebie CAD program, but most quickly run into its limitations and need something else.
The CAD program takes the vector drawing, as well as information about tooling like what size mill bit, what feed rate, the geometry of the mill bit, as well as data about the material thickness and size, type of operation, where the coordinate origin will be, etc., and creates a toolpath, represented in the resulting g-code file that is given to Mach3.
Software is the name of the game here - if you are going to CNC, make sure you budget for the software that will do what you want it to do. If you are going to do only simple things, you might get by with some simple and inexpensive software. Usually, though what happens is that as soon as you realize the wide possibilities with this stuff, you want to do more with it, and the money you spent on the inexpensive stuff is wasted when you realize you wanted something better all along. Generally, you get what you pay for here.
Hope this helps,