Can anyone help or give a good link? Please???

I am dead ordered on doing this myself. My commode is running in my apartment, which wouldn’t be an issue if it were a normal commode with a tank, but my building is old and the pipes go directly into the surround (think like in a bathroom in a restaurant). I’d call the super but the last instance i did that for my running descent they sent up a crackpot team of fix it guys who flooded my bathroom, semidetached my sink from the surround and mitt it uncaulked. I do not want them touching anything again. Can anyone help or give a good link? Please???