짠 and 건배 both are right. There is only a difference in nuance. 건배 > 짠 짠 is more used when it is done with small number of groups or even 2 people. 건배 is only used when it is done with many people like at the party or feast. whatever. and 짠 is a slang 건배 is the proper Korean word.

짠 is similar with "clink". In public situation or with many people, we say "건배". In other expression, we say "위하여". It means " for something ". It can be widely used with 'something', for example "건강을 위하여", "사랑을 위하여", especially for celebrating something. but we just say "위하여" like an idiom, for all good things.