Creating legends for maps

I have a map of the United States.  I am filling colors in certain states.  I need to have a legend at the bottom of the map explaining what the specific color of the state represents.  There are several states with the same color - so, the legend at the bottom of the map will identify the status of the state depending on the color of that state.  I hope I have explained this correctly and look for any help I can receive.  Best regards.

P.S.  The outline of states is one layer; the color for each state is another layer; and the text (state name) is a third layer.