Handicap Calculation for Charlie Boyle for Week 16

Week of Rounds Used:		7	6	4	2		Total		Average		90%		Rounded to:
Gross Score:		64	66	63	62		255		63.75
Hdcp Score (over Par):		24	25	25	22		96		24.00		21.60		22

What does this mean? How are handicaps calculated?