Try http://www.multilang.space/ if you do not need super-profi translation in the beginning.

use TU　ＤＩＥＮ　ＨＡＮ　ＶＩＥＴ　：）

If the name has a meaning , than you could choose similar meaning chinese words to replace that. If not , or it is too hard to translate, than just like Mayalnchina said, by the pronounciation. Here is a more easier way, just say the name to a chinese , let him repeat that , so you will know how that could be in chinese.

Normally, we just use the similar pronouncation. For example: 胡志明(Hu2 Zhi4 Ming2) ==Hồ Chí Minh it is the same vice versa

Vietnam 越南 “yue nan" , vice , as noun means（1） "crime ,evil ,immoral" ,罪恶，不道德的行为 （2）mean 恶劣的， wicked 非常坏的，险恶的,villainous罪恶的，卑鄙可耻的 as "prep" means replace; subtitute for ; 代替，接替