1.
You say ‘Congratulations’ to someone in order to congratulate them on something nice that has happened to them or something good that they have done.
Congratulations, you have a healthy baby boy...
Congratulations to everybody who sent in their ideas.
CONVENTION formulae
2.
If you offer someone your ~, you congratulate them on something nice that has happened to them or on something good that they have done.
The club also offers its ~ to D. Brown on his appointment as president.
N-PLURAL