You are a new student! When changing strings, the inner and outer strings should be changed together. Methods: First, one end of the inner string is wound around the string post on the piano holder, then the other end is inserted into the small hole near the shaft end of the upper piano, and the left hand is rotated from bottom to top until the string is tightened. After hanging one end of the outer string with a ring, the other end passes through the bow, then passes through the daughter, and is inserted into the small hole at the end of the lower piano shaft, and the left hand rotates from top to bottom until the string is tightened. At this time, the piano code is placed in the middle of the python skin of the piano barrel, and the inner and outer strings are pressed on the string groove of the piano code. You're finished. You can practice the piano by tuning the strings.