Hello,
As you know, an appeal is one of the last options in order to get unbanned / unmuted. Whenever you appeal a mute / ban, you should do it like if you were answering a history question.
In an appeal, you must explain the situation (what happened), what did I learn from that, and how will I improve it / how could I improve it.
You just have to be as accurate as possible and, most important, never lie in this kind of situations, as your appeal will never get accepted if you do.
Therefore, you have to express some kind of forgiveness, learn from that mistake, and try to improve on that.
You should know that, in life, people actually learn from their mistakes. So, in this situations, it's very important to make a first step to, eventually, grow and be more mature.