To run the Randomizer, launch the program. Upon opening the program, a window will open with some options.
1. If your ROM is in a .zip file, unzip the ROM prior to running the SMB3 Randomizer.
2. Under the "Original ROM" spot, click on "Choose" to select an unpatched .nes Super Mario Bros. 3 ROM. I have tried to write the Randomizer to not require this, but to be safe, use an original ROM prior to patching.
3. A number will be filled in automatically under the "Seed". You may change this number to anything you would like (for example, an agreed-upon seed for a race). This number may range from 0 to 2^63 (or to be more precise, 9,223,372,036,854,775,807). Any larger number will be coerced into this range.
4. Select the checkboxes corresponding to the options you would like.
5. Click on Generate. The new ROM will be generated in the same directory as the original ROM, with the file name augmented with the seed, and flags corresponding to the options picked. For example, the file name may be Super Mario Bros 3_691556198_cdbm.nes.
6. Open the ROM in your emulator or flash cart of choice. Have fun.