to decide that instead of being upset about something bad that has happened or that you have done, you will learn from it

Okay, so you made a mistake - you just have to put it down to experience and carry on with your life. 好了，你是犯了错误，就把它当作一次教训，继续好好生活吧。

There's nothing we can do about it now, we'll just have to put it down to experience. 现在我们已经无计可施，只能把它当作一次经验教训了。