The tallit blessing should be say before wraping our self with the tallit.
The blessing is:
Baruch Ata Adonai Eloheinu Melech Haolam Asher Kideshanu Bmitzvotav Ve tzivanu Lehitatef BeTzitzit.
The english translation:
Blessed are You Lord, our God, King of the universe, who has sanctified us with His commandments, and commanded us to enwrap ourselves With Tzitzit.