Start by saying Dear editor,
I am writing this letter to inform you on my view of the violent clashes between fans on Saturday. It was mentioned that there was an injury and destruction to the stadium and the neighboring shops. This should not of happened. The community should work on showing a better example for any of the youth that was present at this violent time. The community can better this from happening by dividing sides of the the people on different team to aviod any negative drama.
Sincerely, (your name)
(sorry i really did not know what to write but i hope this helps.)