You don't. Mandarin (chinese) does not have a phonetic alphabet.
Not all English (or foreign) names have an equivalent in the Chinese Language.
Just use the English reading when in doubt, otherwise the Chinese phonetic translation may lead to unintended humourous results.
'Julio' has been translated into the following Chinese phrases before:
julio
Julio no canta muy bien
Julio
July="julio" by the way, in Spanish, months are not capitalized
le dos julio
i want to know how to say my name in Chinese
希望 is how you say wants in Chinese.
i do not know how to say that in chinese but i speak this language.
To say "chess" in Chinese is as follows: 棋
the way to say Chinese in spanish is chino
el siete de julio
Me voy a México en julio