Knighthood was a hereditary title, and was usually passed on by a father to his eldest son.
All prospective knights were trained from childhood in the knightly traditions of chivalry as well as war.
At the age of six, they first became a servant, or page, in another knight''s or lord''s household, where they learned etiquette as well as basic combat, and after a few years they became a squire, an apprentice and personal assistant to a fully fledged knight, responsible for maintaining the knight''s horse and equipment, as well as arming him for battle.
At this point he may choose to remain a squire or become a knight, though many remained a squire due to the restrictions and expense of becoming a knight. Have a look on our 54mm Toy soldier series of Medieval Mounted Knights.