dylantoymaker:
this is exactly what I want to do for a similar basic project. do i need to connect the arduino ground to the negative in on the meanwell or buckpuck?
In most circumstances, yes, you need to have all of your various components all connected to the same DC ground.
By the way I just discovered a neat thing about (some of) the BuckPucks. You can feed them whatever voltage you want for your LEDs (12 to 24V, typically), and get a nice 20mA 5VDC out on a "Ref" pin that can run your Arduino* -- no need for a second power supply. Convenient!
- I'm not entirely sure how many mA an actual Arduino Uno/Deci etc draws by the time you add the various other components on the board... it may be too much. But 20mA is plenty for a bare Atmega328.