If the candidate’s intention is right and he is not disqualified by other factors, he should find a senior monk who can advise him on the places where he might ordain and perhaps recommend him to a preceptor.
If the candidate lives in a non-Buddhist country, he can write for details to the country where he is interested in staying.
Bhikkhus are often travelling and giving Dharma talks around the world and they would generally be very happy to make suggestions about this.
Learn more about the Theravadin Buddhist Monk’s Rules here:
The Bhikkhus’ Rules – Guide for Laypeople