Rather odd that 3 non-native English speakers answer this so authoritatively... But I disagree. I would say "I threw it in the bin". But I'm only a native English speaker. What would I know.

"I threw it in the dustbin" is definitely the best option. You're announcing that you threw it. It addition, it just happened; so past simple is better. "I have thrown it in the dustbin" implies that sometime in your life, you threw it into the bin. It's not so much an announcement that you threw it as much as it is a statement that you have the experience of throwing it. In general when there isn't a time clause, past simple is used like '了' and present perfect is used like '过'. They don't quite match up (especially '了', which is used to describe in change of state), but when talking about events in the past I find they're almost the same.

I have thrown it in the dustbin.

the best answer is "It's in the dustbin" :) use "I threw it in the dustbin".