Instead, maybe use 오빠 축하합니다! or 축하해요!! In korean, often times for colloquial usage the subject is implied within the verb so you dont really need to say 저는 ^^ I don't mean to sound elitist or condescending and if I did im really really sorry :( Just tips for korean use for future asks :)
thank u !!!!! i usually use just 축하해/축하해요 irl & when im replying to them on twitter n stuff i think i just think too much on here bc i try rly hard 2 make sure ppl speak to them respectfully !!! i am rly clumsy omg so pls call out my typos n stuff !!! i even made a typo while writing a curse word in korean yesterday -______- ty tho 4 the help !!!!!