Look up your local high tide time on the “tide times”
link on the tide clock page.

At exactly high tide set the clock to its high tide position (hand pointing straight up) by turning the wheel on the back of the movement, DO NOT physically force the hand round as this will damage the movement.

Insert an AA sized battery (will last around two years).

For best accuracy across a calander month, set or re-set the tide clock on the day of a full moon.