My bedroom has bunk a bunk bed and a closet. ✔

=> Your sentence has a correct grammatical structure, but this has the correct usage/ expression.

B. Make these sentences into English.

(07/19/21)

-어떻게 만들었니? = How did you make it? ✔  => Corrected: The sentence is corrected grammatically.

-간단하지만 저만의 비밀 이예요. = It`s easy but it`s my secret. -> It's simple,but it's secret.

-배부르다.너는 뭐 하고싶니? = I`m full. What do you want to do? -> I'm full. What do you like to do?

=> Another way: Your sentences are okay and these are other ways of saying them.