You paint attributes by selecting surfaces with nodes that have paintable attributes (attributes that are registered in Maya), selecting which paintable attribute you want to paint, and then painting strokes on the node with the Paint Attributes Tool.
The Paint Attributes Tool automatically detects paintable nodes and attributes on the surface, even ones you register yourself. For information on making an attribute paintable, see Make an attribute paintable.
You can define which paintable attributes display in the Paintable Attributes list by clicking the Filter button and selecting the appropriate display filter.