Hi, please i need help with this code:

 public void addCompetitor(String firstName, String lastName) {
    // TODO Implement this method

}

and this:

public void deleteCompetitor(String firstName, String familyName) {
    // TODO Implement this method
}

no, you need a spanking for not paying better attention in class.
As well as for dumping your homework assignment on us, not using code tags, and as usual providing way too little information for anyone to even attempt to help (were we inclined at all to help homework kiddos).