现在完成时是说，到现在为止，过去某个时间发生的动作或者状态到现在才完成，而且这个动作或状态很有可能持续下去。 过去时，就是完全讲过去的事情，跟现在无关。

The rules are surprisingly easy. :) You use present perfect when talking about the present. The sentence tells us about the situation now. You use past simple when talking about the past. It tells us nothing about the present. There are plenty of online quizzes and exercises to practise this. Just have a look! :)

Good question. Its actually there is almost no difference between them because both show the past of something. But i will agree with Ewa and you need to know also that its used for unaccurate time that happened in the past.For example, i have gone to France. You dont mention the time exactlly when. And you say i went to France. Its the same meaning ;)

What is past indefinite tense? Do you mean past simple? You use present perfect when you talk about something what has happened just now, recently or has an significant impact on present situation.