Introduction extended

你好。我叫Douglas。 我是二十五岁。 我去过中国。
Is this correct？In China we say 你好，我叫Douglas，我今年二十五岁（not say 我是二十五岁，the “是” in here  means “is” not “am” you can say 我二十五岁了or 我二十五岁),我去过中国。I hope it can help you.

 The day was dark. The moon watched. Sad, angry, disappointed. The earth is dying.

这个天是黑了。 这个月亮看了。 难过，愤，沮丧。 这个时间弥留。

There are many styles in Chinese poetry.  You have pre-Tang Dynasty styles, the Tang "standard" styles, lyrics and modern.  I'm afraid that I only know more of the standard Tang style... I'm doing as a correction box because of formatting are not removed as in the comment box.

Modern style,  as true to your translation and using your terms as much as possible...

天已黑,

月亮望.

难过,

激憤,

沮丧.

大地弥留.

-----

More or less in a style of a classical standard.  Many things are purposely made oblique.  Chinese does not like things to be too apparent.  One has to infer from between the lines.  Translating back, it does not convey your exact sentiment in your original.  This because of cultural differences.

天上明月照,  Bright is the moon over the sky,

嬋娟姐姐望.  Sister Moon looking down.

悲憤弥留寒,  Sorrow, anger, cold creeping Death.

大地弟弟亡.  Alas Brother Earth soon be dead.

嬋娟 is a literary term for the moon.  望, 寒 and 亡 rhyme.  The reference to the night is omitted.  This is infered from the presence of the bright moon shining.  Here we have established the relationship why the moon is crying for the dying earth.

Introduction extended

你好。我叫Douglas。 我是二十五岁。 我 有去过中国。
Is this correct？

Yes, grammatically correct but like in English, looks and sounds like a beginner.  "How are you? I am Douglas.  I am twenty five years old.  I had been to China."  If you wanted to write like, "How are you? I am Douglas, a twenty five year old who had been to China" becomes something like, 你好, 我叫 Douglas, 今年二＋五 [岁], 已去过中国.

Introduction extended

你好。,我叫Douglas。 我是二十五岁。 我去过中国。
Is this correct？

good job!

Introduction extended

你好。我叫道格拉斯。 我今年二十五岁。 我去过中国。
Is this correct？