There is actually a whole website on idioms which I find really helpful! Here it is - http://www.idiomsite.com/

Have fun!

Yes! The reason l wanna learn idioms is to fully understand what the native speakers say.

I would respectfully disagree with kuno.

It is fine to learn idioms, so that you know what the speaker means, but I suggest you use them sparingly. In my experience, when foreign speakers use local idioms, or swear words, it rarely sounds correct to the native speaker. If it is used in the wrong context, no matter how innocently, it can give a completely wrong meaning. It is better to explicitly say what you want so there is no confusion, but learn as much as you can so that you better understand born speakers.

That is like asking: 中文有多少成语？Just remember to use them as much as possible, but only use when it's correct to do so. Therefore you need to learn lots and lots of them, and then you will have an idiom you can use for nearly every situation.