Saying good morning in Korean is very easy to learn as the most common way is something that you learn from the very beginning. As it’s stated in the graphic above, “안녕하세요” si the most common way people greet each other in the morning.
종은 아침 is also used, but less frequently compared to the former.
The ones in the graphic above are the casual forms of good morning. If you want to be more formal, you can use phrases like:
좋은 아침입니다 = Good morning or literally the morning is good.
잘 주무셨어요? = Did you sleep well? (Used towards people older than you)
Other casual forms for use with friends:
잘 잤어? = Did you sleep well?
Also feel free to write/text these in the morning to friends or your SO.