GecT is correct.
Create an emitter, set your particle render type to "Sphere", and set the rate to the default 100 to test with.
Select the particleShape, then shift-select the plane, and go to Particles > Make Collide.
Select the particleShape, and apply a gravity field.
Basicly, that should do it.
See my attached Maya 8.5 demo scene to see the tweaks I made to things such as spread, direction, GeoConnector resilience (bouncyness), friction, etc.
Learn from it, and check the help for more details regarding specific terms and functions
Israel "Izzy" Long
Motion and Title Design for Broadcast-Film-DS