A good start is watching some tutorials. The web is full of stuff, and even being totally clueless it's easy enough to find something useful. For instance, have a look at this one: https://www.youtube.com/watch?v=RRbrk3SdSKA
But actually, for your purpose you don't have to have really detailed knowledge on CAN. What you have to know is how to control your PC software to send and receive messages, and of course you will finally need a specification of the power supply's CAN interface:
- What messages does it expect?
- What messages is it able to send?
- What's the meaning of the data bytes in the messages?
The PC software is usually bundled with a specific CAN hardware from the same supplier. Kvaser was already mentioned, Vector is another (expensive) one, Intrepid has solutions matching your needs, ...
They all offer professional control software, but also have free libraries to allow interfacing their hardware with your own software solution or third party tools like LabView.
Let me add ETAS Busmaster as another very interesting tool: It can deal with the above mentioned and various other hardware interfaces, it's open source, and it's free of charge.
The Arduino solution mentioned in another answer may be the cheapest from hardware side, but IMHO not the easiest and quickest way to get things running - unless you are willing and able to deal with source code and building your own application more or less "from scratch".