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

Good luck!