V/A+ 으니까/니까 V/A+ 더라.

It is used to deliver new facts that the speaker came to know as a result of what he has seen or experienced in the past. It is not used in conversations with superiors because it is used only in non-honorific language.

For ‘-으니까/니까’, if the stem of an action verb or a descriptive verb ends with a vowel or ‘ㄹ’, you should ‘-으니까’, with another consonant, you should use ‘-니까’.
‘-더라’ is used attached to the stem of an action verb or a descriptive verb.

양이 적어서 배가 찰까 싶었는데 먹고 나니까 배는 부르더라.
I doubted I would be full because of the small amount, but after eating, I felt full.

문제가 어려우니까 시간 내에 못 푸는 학생이 많더라.
There are a lot of students who can’t solve the problem in time because the question is so difficult.

아기가 혼자서는 잘 못 걷는데 손을 잡아주니까 잘 걷더라.
The baby couldn’t walk by himself, but he walked well after I held his hand.

Conversation:

뭘 그렇게 열심히 정리하고 있어?
What are you cleaning up so diligently?

안 보는 책들을 모두 정리해서 기부하려고.
I’m going to clean up all the books I don’t read and donate them.

그래? 책 기부는 어떻게 하는 거야?
Really? How do you donate a book?

인터넷으로 온라인 기증하기를 신청하면 택배 기사가 수거하러 와.
If you apply for an online donation, the courier will pick it up.

홈페이지의 설명대로 따라하니까 별로 어렵지 않더라.
I followed the instructions on the homepage and it wasn’t too difficult to follow the instructions.

안 입는 옷도 기부할 수 있어?
Can you also donate the clothes that you don’t wear?

응, 오염되거나 훼손된 것을 제외하면 대부분 가능해.
Yes, except for those contaminated or damaged, most of them are possible.

나도 옷하고 책을 좀 정리해서 기부해야겠다. 알려줘서 고마워.
I should also arrange my clothes and books to make a donation. Thanks for letting me know.

Related words
기부 donation
온라인(on-line) online
기증 donation
제외 exception

Source: Yonsei University. Korean Language Institute