This doc will teach you the basics of text hacking in roms. We'll be working with Zelda 2: The Adventure of Link (and, later, Final Fantasy 1J in the section on translation). First, you'll follow along with a quick text change just to get your feet wet. Then I'll take you through all the steps you need to know: finding text, making a table file, changing text on your own, and changing font graphics. Finally I'll show you how to put it all together and translate something.
Before we start, you'll need a hex editor of some kind. I prefer Hex Workshop, by BreakPoint Software. Also, I strongly suggest making backup copies of your roms before you start.
1. Getting Started
2. Finding Text in a Rom
3. Making a Table File
4. Changing Font Graphics
5. Translation Hacking