How to calculate the date of each month with heavenly stems and earthly branches?

The calculation of the month and month of the main branch is based on the formula of "five tigers make a Song Yuan": C is the first in Jiaxu year, and E is the first in Yigeng year. Bing Xin's age is counted from Geng Xu, and Ding Ren asks for the first month. Built in the first month, ten years will be smooth. His song also said: A is the first of three, and B is the first of five. C Xin seeks to live in a circle from Geng Yin, Ding Yin and Wu Yin. Second, the determination of the monthly branch is relatively simple. Twelve months correspond to twelve branches as follows: the first month, the end of February, the morning of March, the end of April, the afternoon of May, the end of June, the application of July, the integration of August, the end of September, the sea of October, eleven sons and twelve ugliness. It should be noted here that the starting time of the lunar branch is not based on the first day of each month, but on the 24 solar terms of the lunar calendar, which is why there is no independent calendar for the lunar leap month. Yin from beginning of spring to Jingzhe, Mao from Jingzhe to Qingming, Chen from Qingming to Changxia, Changxia to Mangzi, Noon from Mangzi to Xiaoshu, not from Xiaoshu to beginning of autumn, Shen Congli's autumn to Bailu, especially from Bailu to Hanlu, Xu from Hanlu to beginning of winter, the sea from beginning of winter to heavy snow, purple from heavy snow to slight cold, and ugliness from slight cold to beginning of spring.