To use this interpreter, simply copy-and-paste your code into the large text box and hit the Run! button. The program output will appear below where it says "output."
If the program requires input, a little box will pop up asking you to type something. Please do not type more than one letter; if you do, the program will only receive the first letter you type. Some browsers may block the input window depending on your security settings.
If you're looking for information about the Brainf**k programming language, this page will help. If you want some programs with which to test your own interpreter (or this one), you should go here.