I've gotten several requests for help with doing game corruptions. So, I've decided to make up a little beginner's guide to doing them. First, you'll need 3 things: The Vinesauce ROM corruptor, game ROMs, and emulators that can run said ROMs. I'm too lazy to hunt down links, so Google is your friend in finding these things.
Now, run the Vinesauce ROM corruptor. I'll point out the things you need to familiarize yourself with. First, notice the "ROM Directory" box on the top-left. Use the file browser to find the folder with your ROMs in it, and set it to that. You should see all available ROMs appear in the box under it. In "Save Corrupted ROM To", just pick a directory that exists. For me, I save in my main ROM folder; you can use desktop or whatever is easiest for you. I'd keep "Overwrite File" checked, unless you plan on saving multiple corruptions to play later. In "Emulator To Run", browse to find the desired emulator to play your selected ROM; have "Run Emulator After Corrupting" checked for ease of use.
Now, with that basic stuff out of the way, there are 3 ways to mess with your games that you'll notice: Text Replacement, Color Replacement, and Byte Corruption. You probably won't have much desire to mess with the first 2, but I'll give you a brief overview. Enabling "Text Replacement" will let you replace words in the text with other words, provided they have the same number of characters. Also note that they are case-sensitive, and the NES generally only uses capital letters. That's about it. "Color Replacement" is mostly the same. I've never messed with it, but I believe it only works with NES games. Just pick a color to replace with another color. That's it.
The right side is where all the magic happens. Click the checkbox next to "Byte Corruption" and buckle in. Now, the methods and difficulty in corrupting a game depends mostly on the game. A general rule of thumb is also that games become harder to corrupt the larger they are. To put it simply, NES games are relatively easy to corrupt, SNES games are much trickier, and N64 games are really hard. I've only messed with NES and SNES games so far, so I'll give you a step-by-step guide to corrupting NES games, and then explain how to modify the approach for SNES games.
* Check the box next to "Auto End"
* Set "Increment" to 1000 (should be the default)
* "Corrupt Every" should generally be a number between 500 and 4000. Lower numbers equal more corruption.
* Choose either "Add" or "Shift Right" and set the number to 2
* Choose your starting byte by clicking the + button after "Start Byte". You can try to start on byte 0, but it will crash more often than not.
* Click "Run"
You may get something playable, or you may get a crash. To get different corruptions, increase Start Byte, Add, or Shift Right, or change the Corrupt Every number. Do note that if you set your Add or Shift Right numbers too high, it simply won't do anything. Also, note that you can check the "Enable NES CPU Jam Protection" box if you keep getting CPU jams. This will lessen the amount of corruption you get, but may prevent crashes. I suggest using the emulator Nestopia for NES corruptions, since its rewind feature can help you deal with some of your corruptions' bullshit.
Now, for SNES games, you'll need to make some changes. First of all, since the games are much bigger, I'd recommend setting your Increment to 5000, or 3000 if you're trying to be precise. You also may have a very hard time getting any corruptions to work with "Auto End" turned on, especially if you're using a lower number in "Corrupt Every". Generally speaking, you'll need to adjust both the Start and End Byte numbers. Get them relatively close to each other, but not too close; a couple thousand apart, at least. Also, when doing it this way, you can feel free to set "Corrupt Every" to a very low number if you like. One thing to bear in mind (that I just learned) is that different data is stored in different bit ranges. For example, the early bit ranges may control the background, while the mid controls sprites and the high controls music. Don't be afraid to move your Start Byte all around.
That's about it. Corrupting is certainly not a science, and requires a lot of trial and error. Also, some games just don't want to corrupt at all.