[Nagoyankee]

くにおくん、こんにちは！ようこそＪＦへ！

にほんごのべんきょうはたのしいですか。

Glad to hear another JF member is studying our language. Moreover, I'm happy to learn that you are studying it using kana right from the beginning because romaji is never the real thing.

What you wrote in hiragana and romaji is basically correct, but I'd like to make a few suggetsions to make it perfect.

Konnichiwa everyone. > I know this isn't totally Japanese but the natural word order is the reverse. We say みなさんこんにちは.

にほんごものすごいです。 This needs a particle. > にほんごはものすごいです。

Add another word and it will sound even better. ことば　＝ a language.

「にほんごはものすごいことばです。」