How do you know what ending to put on a name in japanese? like in the anime's thiers kei-kun meiko-chan ect. does it go by gender or formality I've been wondering for some time now if someone could answer it for me i would greatly appreciate it. thank you

Welcome to Jdorama. The suffix used to address a person is quite easy to understand:

san - A formal term which is applicable to both male and female.
kun - A casual term usually used to address a male that is younger or lower in status (a kouhei).
chan - A general term to address children that is applicable to both male and female.
sama - A formal term used to address someone of higher status, applicable to both male and female.
dono - Even more formal than 'sama', used mostly in writing only nowadays.

could you have some ones name in wwritting like that or only when adressing in person.. example......suki(<last name) yukiko san?

jeshatt erkis wrote:

could you have some ones name in wwritting like that or only when adressing in person.. example......suki(<last name) yukiko san?

'Dono' is used nearly only in writing nowadays. The rest is used in both speech and writing.