We use the Present Continuous when talking about an action which is still is progress.

Tom wears a suit at work (Present Simple - what he usually does), but now he is wearing a T-shirt (Present Continuous - what he is doing now).

I'm playing tennis now. (in this moment)

I'm reading a good book. (not necessarily at the time of speaking, but also when you started a book earlier and it's waiting for you at home)

I speak French (Present Simple - refers to something which is true in general), but now I'm speaking English (Present Continuous - refers to something happening now).

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We use Present Perfect when the action is still in progress or has an effect on the present.

If you can't find your key, you can say: I've lost my key. (you can't find it, so it has an effect on the present)

After finding your key, losing it doesn't have an effect on the present any more, so it's used in the Past Simple now: I lost my key but now I've found it. (now it's "finding" that has an effect on the present)

For general questions like this, you can simply look them up. Search for "English grammar present perfect", for example.

http://www.englishpage.com/verbpage/presentperfect.html

http://www.englishpage.com/verbpage/presentcontinuous.html

The greatest thing is being nice, you are more than that, thank you for what you are.

Thanks a lot for Mr. Peachey your piece of advice.