When modding Fable, a hex editor is an essential tool. Although user-friendly utilities are developed for many functions and are being created for even more, these things all had to start somewhere. This “somewhere” is with a hex editor. Things that are now do-able with a click of your mouse used to be done tediously through deliberate modification of numbers. The goal of this “guide” is to take you through just what a hex editor is, what it does, how to use it, and why you're going to need it if you expect to be any good at modding Fable.
First off, a hex editor is essentially a tool that will open up any file on your computer and display all the information in it in hexadecimal digits. These, if you are not familiar with the series, do not go from 1 to 10 but rather 1 to 16. Therefore it is counted to the effect of 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F, 10, where F is 15 and 10 is 16. Everything on your computer is arranged in this way. The hex editor will open the file and display all this numbers that make up the file on your computer (as well as text associated with it, but I'll get to that in a minute) so that you can see them and edit them. The most popular hex editor is Hex Workshop, which most of us use. It is available at http://www.bpsoft.com/.
So now that you know what a hex editor is, you need to know what it does (which should help you start to understand why you need one) Since every single piece of information on your computer can be translated into numbers as shown above, it can just as easily be modified. A hex editor will, aside from displaying the numbers that make up the file and usually text as well1, give you the ability to modify the data by simply changing those numbers. In hexadecimal, everything is made up of “bytes”. I guess for now you can view these as pairs of digits. There are two digits in every byte. You've heard of kilobytes, and such… well, that just refers to (close to) one thousand of these pairs of digits. Editing different pieces will obviously have different effects.
Hex editing basically only requires common sense and some background knowledge (the amount needed varies depending on what you're doing) This is to say that you can not go into a file and just randomly start changing numbers, because you're likely to destroy the file this way. The CTRL+F button is your friend, as are bookmarks. We have lots of information on the hex components of different files so you can find out how to edit what you need (that is, if we have found out how to edit them) Realy all I would recommend doing is playing around with your hex editor, trying to understand what you know and trying to improve on it. When it comes to this, experience is sort of the best teacher for a beginner.
There are lots of things we still can't do with easy-to-use utilities. Fable Explorer isn't always efficient in file swapping, for example. But even beyond that it's good to have a grasp on hex editing because as more details come out from those who are putting in effort to crack mostly-untouched formats, the only way you'll be able to modify them for a long time will be with a hex editor. That's sort of always been the case.
1. Text is displayed on a window to the side, usually, because certain bytes can be interpreted as text. “X”, for example, is 58. There are different bytes for different cases, as well. While “X” is 58, “x” is 78. This is how text files work (DOCs, TXTs, etc) But remember; just because the bytes can be turned into text doesn't mean they're necessarily meant to be.