I want to learn the 56 instructions and the hardware like, registers, ALU or whatever. Where can I learn that?

Due to its enormous proliferation, as well as its role in shaping computer history, the 6502 is arguably the most documented microprocessor ever designed. Everything you could possibly want to know about it is as close as the nearest Internet search engine.

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x86?  We ain't got no x86.  We don't NEED no stinking x86!

The best tutorial and reference I know of is the programming manual "Programming the 65816 including the 6502, 65C02, and 65802"" by David Eyes and Ron Lichty. It's not free anymore, but it's definitely worth the price. No 65xx enthusiast should be without it. The 65c02, BTW, has more instructions than the 56 number you gave (it's around 72), and more addressing modes too, and the 65816 has even more. If you're just getting into this, do not limit yourself to the original NMOS 6502's instruction set.

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http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?

Another thing that might well help you is that the Kowalski simulator shows you information about the instruction at your text cursor as you edit. This means you're getting given little clues as you go.

Oh, and although it is Windows software it does seem to work under Wine.

I'll quote myself from another thread:

Note however that these older works are only about the original 6502 instruction set. That's quite enough to learn about how to use a 6502, but the 65C02 does offer some extra instructions which help a little with performance and code density, and the 65816 goes a lot further.

Thank you so much! This is the best tutorial ever =]