If you want to send a message to a character from an anime please include the following 

Hi/Hello/Dear/etc...[Characters name] 
(Your message) 
Love/From/Yours Truly/etc....
[Your username] 

And please tell me which anime they are from because I know some anime characters with the same name as other anime characters 

Once you send the letter to them then they will read and reply to your letter, I hope you enjoy ;)