How to ask somebody else to write PHP articles?

We often need PHP related articles, if we do not have enough time, we can ask other PHPer for help. Here is an example on how to find good PHPer to write for you:

I am looking for someone to write me 10×500 word articles for the PHP Study niche (keywords to be given when we reach an agreement).

I will pay $20 for the 10 articles but please only contact me if:

1- You are a native english speaker or someone that can write near-perfect English. I want the articles to really make sense.

2- I want the articles to be relevant and not just some fluff to fill the 500 words. Make it informative and appealing.
3- All articles should have quality unique content, not just rewrite others articles. If you have PHP knowledge, you will have more chances to get the job.

Please send me a short sample of your work.

If you think you can write me the 10 articles the way I want them then please contact me asap. If we can cooperate well, I will need more PHP articles every month.