Japanese names and Kanji?

Question:

Alright in another question someone explained to me how Kanji works..
And how it works with names, but I still don't really get it. Two persons in my book are called Naoki and Hiroto (they're boys)

Naoki means Honest Tree.. So does that mean that you have to write it like this:
直 (nao) "honest, straight" and 樹 (ki) "tree"?
Hiroto means Big Flight: 大 (hiro) "large, great" and 翔 (to) "soar, fly"?

Or can you do it different? Many people say there are many ways to write it, and I get why (see my other question and the very good explanation) but then how do you explain how you write your name? Cuz here in the netherlands it's like: Hi i'm Margreet.. and people react with: Oh alright.. with a H on the end or not? And then I'll tell them it's not. Or I'll spell it out for them. But that's not possible with Naoki en Hiroto right?

BTW do you ALWAYS write your name in Kanji or sometimes also in western letters?

Thanks!

Answer:

Japanese names are the most difficult to understand (to explain) because there are so many ways to write one name. Even for Japanese, sometimes, it is hard to guess the kanji from the sound of the name or guess how to read it just looking at the kanji.
When we name a child, we usually choose name first, then decide which kanji to use it. Sometimes, kanji are chosen because of the sound matches the name, not always the meaning of the kanji itself. Also, kanji are chosen by the sound and the number of strokes to write(kakusuu画数) by superstitious reasons.
We often explain which kanji by referring simple common words, just like "V as in Victory".
So, if my name was Naoki. I would explain (to Japanese) like "kanji for Nao is Jiki in Sho-jiki正直（Honest), and jyu as in jyumoku（樹木）”
Although mine is very common Japanese name,the Kanji for my name is very rare, so I often have to write it down to explain. Most of Japanese people cannot read it. Thanks to the scholar who named me when I was born.
When we write official papers or documents, we always use Kanji unless your legal name has to be written in Hiragana (or Katakana). We use western letters if we are writing to the people outside Japan.
I hope this help.