How to find the "dragon head" of "Dragon Head Up"?

The ancients divided the astrology near the ecliptic into 28 constellations, which were divided into "four constellations" in four directions: east, west, black dragon, white tiger, Suzaku in the south and Xuanwu in the north. The seven huts in the East are called Jiao, Kang, Bian, Fang, Xin, Wei and Ji respectively, forming the image of a dragon, in which Jiao stands for "dragon head".

Around the second day of the second lunar month, at the beginning of spring ploughing, Seven Nights of the Black Dragon began to rise slowly on the eastern horizon. The first night was the "dragon head" corner, and the whole body of the black dragon was still hidden below the horizon, which was vividly called "dragon head" by the ancients.

The first time you see a corner beam, you can look for it in the following ways: look up at the northeast sky and find the familiar "Big Dipper". Along the curve of the handle of the Big Dipper, we can find what we in China generally call arcturus's Mufu Alpha, which is also the fourth brightest star in the whole night sky. Continue to stretch forward, you will see a bright blue and white star "arcturus", and you will find arcturus. Not far to the left of arcturus, a dark star is arcturus II. Find "Jiao Su Yi" and "Jiao Su Er", and you will find "Jiao Su", the first of the seven hotels of the Black Dragon, which is the "dragon head" in the East.