If you want to know how to write poetry, the first thing you have to do is write some. It doesn't matter how it turns out. Your own mistakes will become your teachers. Your own writing will motivate you to greater creativity. Now, once you start the process, how do you improve it? Here are three tips.
1. Use nouns and verbs more than adjectives. Which is stronger: "She was as beautiful as a flower..." or "Roses wilted in shame as she passed by..."? "He looked at the depressing clouds..." or "He watched as dark clouds moved in, covering his sky..."?
2. Don't tell the reader how to feel. Let the words elicit the emotions directly, without explaining. "The tragedy touched them all," is more touching to the reader as "Men and women, doctor and workman... thirteen people looked upon the scene... with tears in their eyes."
3. Use dramatic and emotional words. Not all words are equal in their ability to "grab" a reader or elicit emotion. "Fell," "take," and "love," will probably be weaker than "plunged," "siezed," and "worship."
Look at the following lines, written two ways. The second way applies the three rules above. (From the poem "Gratitude.")
The mountains and lakes were beautiful
I looked at them, heard them and smelled them
And I felt in awe
Mountains stand against the sky
My little lake at their feet
And in the middle of this creation
Which I see with my eyes
Hear with my ears
Smell and taste...
Words fail, as they should
I hope you agree that the second version is better. Again, if you want to know how to write poetry, you have to start writing. Use these and other rules to help you, but remember that all rules in poetry need to be broken at times. Read your poems aloud to yourself and others as a final "test."