What is the proof originally given by Pythagorus? Help me please. I took a right angled triangle and then on each side I marked a square. After that, I do not know how to proceed? Any hint or clue please?
The answer to the first can be found >>here<<, and to the second the answer is we do not know.
The link above gives, among others, Euclid's proof which may be what you are really asking about, or may be not.
This website, Pythagorean Theorem and its many proofs, gives 39 different proofs, starting with the one Euclid gave in his book. As Captain Black says, no one knows whether or not Pythagoras really proved it, much less what that proof might be.
Notice that proof #5 was first given by James Garfield, before he became President of the United States (there is no evidence that he was elected president because of the proof).