Good morning

Dobroye utro

Good day

Dobriy den'

Good evening

Dobriy vecher

How are you doing?

Kak dela?

Thank you, I'm good.

Spasibo, khorosho

I'm fine

Normal'no

Bad

Plocho

See ya!

Poka

Happy new year

S Novym godom

Merry Christmas

S Rojdestvom

Happy birthday

S Dnyom Rojdenya

In Russian's old calendar, 7th of January is Christmas! They celebrate it together with New Year.