Law of the poet can be divided into moral and economic. In the first case, the author has the right to be referred to as the Creator of the work. He could publish the poem anywhere. Property rights the author may transfer to another person (for example, the publisher). If necessary, property rights are extended. It is also important to know that copyrights take effect from the time of writing the poem, and when the time of death of the author will be 70 years, the work becomes public property and it is entitled to use any person (Directors to make a film on the works of Tolstoy, don't have to get any permission).
Unfortunately, you can't come to any sort of national organization with their poems and make them a author. But as much as possible to protect yourself from plagiatchikov you still can.
The vast majority of authors do not have the ability to publish their works independently, as this process is very expensive, and doing it through a publisher. Safeguard your copyright will become a contract with this publishing house, in which you transfer the right to publish your poems. Carefully read the document and make sure that all clauses are acceptable to you. If you have any doubt better consult with a lawyer.
If you never plan to publish and write poems for my own pleasure, posting the results of creative blog or at special sites to protect yourself from attacks will be more difficult. Be sure to keep the computer source code. If there is a dispute, who is the author, the proof would be the document creation date.
A great way to protect your copyright is to send letters with poems to yourself. In this situation, proof of time of creation will be the postmark on the envelope.