I did nothing

Next question raised by one of Arabic learners, is..

How to say:

I am not doing anything, or I did nothing

Tak buat apa-apa pun..

Suggestions:

لاَ أَفْعَل شَيْئاً
La af'al shayan
I don't do anything


مَا فَعَلْتُ شَيْئاً
Ma fa`altu shayan
I did nothing

any comment?