You can apply one color, pattern, or gradient
to an entire object, or you can use Live Paint groups and apply
different colors to different faces within the object.
Select the object.
Click the Fill box in the Tools panel or the Color panel.
Doing so indicates that you want to apply a fill rather than a stroke.
Fill box
Select a fill color by doing one of the following:
Click a color in the Control panel, Color
panel, Swatches panel, Gradient panel, or a swatch library.
Double-click the Fill box and select a color from
the Color Picker.
Select the Eyedropper tool and Alt‑click (Windows)
or Option-click (Mac OS) an object to apply the current
attributes, including the current fill and stroke.
Click the None button to
remove the object’s current fill.
You can quickly apply color to an unselected
object by dragging a color from the Fill box, Color panel, Gradient
panel, or Swatches panel onto the object. Dragging does not work
on Live Paint groups.