Someone can teach me to do this kind of things, explaining step by step, and with simplistic words, like attempting to teach a 8 Y.O. child? I wanna learn, but theres no good tutorials of this kind in my language, or there are too technical for me.
I understand that if English isn't your first language, it can be hard when most of the help is in English (although your English seems rather good to me
). The reality is that a real ROM hacker doesn't need to be stepped through things like an 8yo child. Rather, like a real 8yo child, a real ROM hacker just figures things out because they want to. A decent tutorial or some helpful words should be the beginning, not the end.
I can think of several bits of help that really pushed me to do amazing things. One was a user on this forum sending me a PM telling me how a little bit of assembly knowledge would improve one of my hacks, as what he showed me made me realise that assembly isn't all that hard, and I began to learn more as a result. Another thing that helped me after that was KingMike's tutorial about dual tile encoding, because I had just started to figure out how assembly worked, and seeing an actual example with clear explanations of how it worked sparked things off for me, so much so that I was then able to write my own routines for DTE and other things, and recently I was even able to crack a graphics compression scheme in a game.
These few things made a difference to me, which is why I try to help people on the forum - but not just do things for them. With a bit of a push in the right direction, and with a lot of patience and the right attitude, you can do it.
Regarding your question about the table file, that's the basic idea. You see, eventually the game has to see some values in the RAM to draw things on the screen. In the case of the NES, the area from $0000 to $1FFF in the PPU memory is the pattern table, which is what the graphics look like. It doesn't include the colour palette, just what each colour the pixels are (out of four possibilities). From $2000 to $27FF is the two name tables (there are two full screens), which say where everything from the pattern table should be placed on the screen.
So let's say for example that $2152 in VRAM is 93 - this means that tile number 93 is here. Tile number 93 refers to either $0930-093F or $1930-193F. So, if you want to know how to read the data in the ROM as text, you have to know how the game ended up putting 93 in that part of VRAM. It may simply be that 93 is a letter of the alphabet, and the rest of the alphabet follows logically, but not necessarily. In the case of Sunman, the letters are on alternate spaces in the Pattern Table (02, 04, 06 etc) but in the ROM, the text is stored without those spaces (01, 02, 03 etc). The way to be sure of this is learning assembly, but again, it's not hard once you get started.
I've said a lot, but the point is just to explain that by working on things a little bit, you can do a lot. There are good tutorials out there, but you need to try yourself a bit. Good luck!