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Yes, very good job. I would personally not put flash in manual power until you get used to the other variables, but definitely would have dragged the shutter to a little slower speed to get more ambient light. It took me a while to have confidence enough that the flash would freeze the subject at slow shutter speeds, but it really does work - as long as you don't drag so much that the ambient becomes the main light.
I don't think he set the flash to manual, rather he had the camera set to M mode. He had previously solicited advice on another thread...
BTW, nicely done Campy.
As others have mentioned, if you can, it's a good idea to mix in a little ambient light in the background. This usually requires bumping up the ISO and/or "dragging" the shutter a bit (using a slower shutter speed along with 2nd curtain sync). That said, it's hard to tell, but there doesn't seem to be that much background lighting in the venue, judging by your shots. I'd say you did fine under the circumstances.