Still can't understand the twin paradox...experiement a constant speed blew my head off!!?

"Lower clocks go slower," describes the real affect that in higher strength gravitational fields time goes slower - than in lower strength gravitational fields. But, the same is true if a clock experiences acceleration. The clock can be any natural physical process such as the vibration of a tuning fork. What happens to photons then, and their ociated frequencies/wavelengths? How does this fit with "E = hn"?