The earth revolves once a day. The moon's gravity pulls on the oceans and raises the water a few feet. But it isn't on the part of the earth directly facing the moon that the oceans rise, it's at the edges. I
n other words, if you drew a diagram with the earth on the left and the moon on the right, high tides would be at the top and bottom of the earth, as you are seeing it in that view. You are looking at the earth roughly from the north or south pole. So now imagine the earth revolving, but those bulges in the oceans remain in the same place. So as the earth revolves one time, you get two high tides.
The sun also affects the tides but not nearly as much. When the sun is lined up with the moon, they pull together--the sun's pull is added to the moon's pull, so the tides are higher. When the sun is on the opposite side of the earth from the moon, then the sun's pull is subtracted from the moon's pull, so the tides are less.
When the moon is full, that's because the sun is on the opposite side of the earth, lighting the moon completely from our point of view. So that's when tides are at their lowest ('neap tide'). When the moon is 'new', that's because the sun and moon are on the same side of the earth, so that's when the tide is highest ('spring tide').
The earth rotates at 1 revolution per day. The moon revolves the earth at one revolution in 29 1/2 days. And the earth revolves around the sun in 365 1/4 days. So the math can get a little complicated. 8^)