こんにちわは!

こんにちわは! にほんご おを べんきょう しています! みすミス おを しゅ-うせい して ください!

Your writing was very good and fully understandable!
The only thing I can suggest is that you should be careful about the particle を. It has the same pronunciation as お, but お cannot work as a particle. At the same time, the hiragana を is very unique and used only as a particle. Also, we basically write loanwords like ミス(miss) in katakana.

Keep up the good work!