[number] + 点 + [number] + 分 [number] + 点半 [number] + 点 + 一刻 / 三刻 差 + [number] + 分 + [number] + 点
Clock time is built from 点 for the hour and 分 for the minutes, largest unit first.
Chinese counts minutes forward through the hour, so "ten to eight" is 七点五十分. The 分 can be dropped when the number is two digits: 三点二十.
三刻 is three quarters past, so 六点三刻 is quarter to seven.
Two o'clock takes 两, because 点 is a measure word. The minutes keep 二: 两点二十.
几点 asks the time, because the answer is a small number.
上午, 下午 and 晚上 come before the hour: 下午三点, 晚上八点.