Just write in a common format. When you give a red envelope, just give it to your classmates, and they will know that you have come to congratulate them on marrying their daughter. As shown in the figure. If you don't have this wedding red envelope, buy a red envelope of other styles, move this format and write it on the back of the red envelope. The middle greetings can also be replaced by "a hundred years of harmony", "eternal harmony" and "dragon and phoenix are auspicious", which are not necessarily "wedding anniversary"