The two sentences that best explain how Poe creates irony in the story are:
1. **The narrator’s attempts to hide the murder actually result in him giving himself up to the police.**
2. **The more the narrator insists that he is not mad, the more readers can detect evidence of his madness.**
These sentences illustrate the central irony of the story: the narrator's efforts to conceal his crime ultimately lead to his downfall, and his denial of insanity reveals his unstable mental state to the readers.