First thing its not a lesson to give it in detail. mostly if you know your partner is a cheater its easy to get evidence. but if your partner only cheated once then its impossible.
Secondly no not only 4, but 4 honest sane men to witness. 3 if he is a man because he will be the 4th
Third thing is that if the person say I'm innocent, he must say wa Allah 4 times, if he\she is lying the person will have the anger of GOD upon him.
https://islamqa.info/ar/192233
if you don't know Arabic you need either a very good translation or an Arabic person to read it for you.
If a person know that his\her husband\wife cheating, will only have to bring 4 sane honest men to witness the sin its not impossible to do.
If the 4 men lied they will have to pay the sin of gathf
lastly if you want to put details put it in full.