Tidally locked and not rotating are 2 different things. The Moon is tidally locked to the Earth so we only see one face. The Moon rotates once every 27 days and orbits us once every 27 days. Mercury is tidally locked to the Sun.

Pick up a ball and have it "orbit" a lightbulb at home. A solar day (noon to noon) should be a year.

"Dark side" of the moon is a misnomer. All sides receive the same amount of sunlight. It's just generally people automatically assume the far side is always dark, and movies don't help.