Japanese Hiragana, Katakana, and Kanji.?

I'm afraid I can't understand well what your question is as I'm not an English speaker, but

I guess:

Commonly Hiragana is used, mixed with Kanji like 鳥が飛んでいる.

Kanji repesents the meaning of a Kanji.

With Kanji in Japanese, we can easily, smoothly understand what a sentence means.

What is more, without kanji, we can't smoothly read sentences written by all Hiragana because of its chaos. That is the case.

As you are a foreigner, now you might use Hiragana a lot.

But we don't write sentences using only Hiragana.

When I need to write a letter, or Kanji that I don't know how to write, I, we use Hiragana, instead of the Kanji I don't know.

Commonly Katakana is not used except for particular ways/occasions.

For example, words from foreign countries, such as ドア, ボール、etc.

There are also other ways to use Katakana.

Although there are three ways, there is only one method to write Japanese.

No one writes all Hiragana sentences except for small children.

No one writes all Katakana sentences, if any, except for particular occasions.

No one writes all Kanji sentences, which we can't write.

You should write Japanese useing Kanji, even if a little, mixed with Hiragana, then your letter looks beautiful to us, and becomes easy to read.

Hiragana/Katakana aren't really "letters", they are sounds. There is no different dialects.

Hiragana is used for Japanese words, people from Japan also spell there names in Hiragana.

Katakana is for foreign words. Foreigners spell out their name in Katakana. Also, Japanese borrowed some words from other languages (like "Diet") and they spell those words out in Katakana.

Kanji are used to represent words, so it will be easier to read and avoid confusion. For example, "Kami" in Japanese means "God", "Hair", and "Paper". If you write "Kami" down in Hiragana people will ask you which Kami you are talking about. This is where is Kanji used-- God, Hair and Paper all have different Kanjis but are all read the same.