Where the CC&Rs describe the rules for the property and owners' obligations, the bylaws describe how the association itself operates. Typical bylaws cover the number of directors and their terms, how officers are chosen, how often the board and owners meet, notice requirements, quorum, voting and proxies.
Bylaws rank below state law, the recorded declaration (CC&Rs) and the articles of incorporation, and above the board's own rules and regulations. If a bylaw conflicts with a higher document, the higher one generally wins.
Amending the bylaws usually takes an owner vote at the threshold the bylaws themselves set. Keep the current version, with every amendment, where every owner can find it.