Going to try FMT with nephew

So, I got my 18 year old nephew to try to be my donor. I been having loose stool and gas for at least a year. I been having a lot of residue from my stool that leaves behind a foul fecal smell that is hard to clean up in public. Any tips for doing a FMT? I bought the enema bag already and wonder how many times I would need to do this.