You can register a TLD through a TLD Registrar.
there are several organizations
that register TLDs on the Internet.
However not all of them are approved and accredited by the by the
Internet Names Authorization &
Information Center (INAIC). The organizations that are approved and accredited by the INAIC are listed here
You may select one of these TLD Registrars to register your TLD.
Please note that not all TLD Registrars have an on-line registry available. The terms and conditions may vary depending on the TLD Registrar. Due to international agreements all two-character TLDs are reserved as country code identifiers. Two-character TLDs (ccTLDs or Country Code TLDs) can only registered through IANA
to learn more about TLD Registrars.