You can select polygon faces or NURBS surface points and then assign hair follicles to these locations.
To create nHair on selected components
Select faces for polygon objects and surface points for NURBS surfaces.
See Output.
For descriptions of the hair options, see nHair > Create Hair.
The selected object components are populated with hair follicles. Use nHair > Randomize Follicles to add randomization values to the follicle locations to adjust the placement of follicles.
By default, nHair collides with passive collision objects. If you are adding nHair to a NURBS surface, you must convert the object to a polygon object before the hair collides with a surface object. See Creating nHair on surfaces.