I want to know the correct usage "for you" vs "to you" for example:
Congratulations for you too.
Congratulations to you too.
Which sentence is correct?
The idiomatically correct way to say it is "Congratulations to you too."
English prepositions are very difficult to learn, because there are not a lot of rules and you mostly just have to learn every case separately. In general, if you can imagine yourself "sending" feelings like congratulations or thanks, the appropriate preposition is to.
But we also say
I am thinking of you (or about you)
I have great hopes for you
I have great faith in you
I wish you the best of luck (no preposition!)
So as you can see a lot of it depends on the exact sentence you use. In the case of "congratulations", it's always to.
The second sentence is the correct one. Here are some more examples:
Congratulations to you!
Congratulations on winning the competition!
Congratulations to you both for winning the competition!