How does one report someone to the credit bureau who has not paid debt?

You don't. Credit bureaus are regulated businesses who accept entries from their paying clients. Those clients must meet legal criteria to access and imput data to a consumers' credit file. There is no way that an individual would qualify, even if that person were willing to pay the fees. An individual has the option of filing a case against someone who owes them money. Given proof that withstands the rigors of law; if a judgment were granted, that judgment would be recorded in the public records. This type of public record is routinely included in credit reports.