The sample count is at the bottom of the Luxrender window, in the satatus bar. As the Reality User's Guide states, you need to have a few hundreds or a couple of thousand samples to get an image without noise. You can find all details in the Reality User's Guide, wich is installed in the docs folder of Studio.

Paolo

https://www.preta3d.com
FB: https://www.facebook.com/RealityPlugIn
Tw: @preta3d
G+: https://plus.google.com/106625816153304163119
The Reality Gallery: https://reality-plug-in.deviantart.com