Happy Easter to everybody who celebrates this holiday! 

По-русски: Со све́тлым пра́здником Па́схи! 

Let’s look into the phrase structure:  preposition Со (we add О to C as the following word begins with С too)+ све́тлый пра́здник Па́схи in Instrumental case (literally with a bright holiday of Easter).

Another, more religious way to congratulate on this Day is to say: Христо́с воскре́с! Christ is risen! And the answer should be Вои́стину воскре́с! Indeed, He is risen!

Want to know some more facts and learn Russian Easter and download Easter Vocabulary List with Grammar comments and pronunciation? Continue reading here: http://www.ruslango.com/2017/04/15/russian-easter-related-vocabulary/