At first glance, their website says the fixture will do RGB color-mixing so, yes, you should be able to do it. I'm guessing this is your first attempt at DMX? If so, let me throw a couple of things at you.
The fixture address will tell you what fixture button (the left-hand dozen buttons on your controller) will activate them. I'm willing to guess the fixtures come default at address 1 which is button #1. Here's the layout of button addresses:
button 1 - address 1
button 2 - address 17
button 3 - address 33
button 4 - address 48
etc. etc
If your fixture is at address #1 then the RGB controlls will probably be sliders 1,2,3 (address 1,2,3). Basically put, the sliders begin at the first address point then each slider is the next logical address #. There's a "Page Select" button that toggles the banks of 8 sliders. If you're working with fixture #1, address #1, then "Page A" will have sliders assigned to 1 - 8. If it's in "Page B" sliders are assigned to 9-16.
If I'm incorrect on the above I'm sure someone will straighten me out but hopefully this will help. Oh yea, be certain to use DMX cable. Some guys get away with standard mic cables but on my Obey 40s, it never works. Good luck.