What would be an example of propaganda?

Propaganda is different than persuasion. A propagandist is only interested in achieving his goals. Persuasion involves a dialogue between two parties. If I'm attempting to persuade you, I make my goals clear, state my case, listen to your concerns, adjust my goals as necessary, etc. Ideally, both sides win.

That's not the case with propaganda, which is one-sided with the goals of the propagandist concealed. A propagandist attempts to achieve his goals at all costs.