To write content around a low competition keyword phrase to get a higher search engine rank for that keyword, you need to do the following:

1. Include the keyword phrase in your title.
2. Include the keyword phrase in your meta description and keyword tags.
3. Include the keyword phrase in at least one header tag at the top of your page.
4. Include it 3 to 4 times in the first paragraph.
5. Sprinkle it throughout the rest of your text.
6. Put your keyword phrase in italics and/or bold in a couple of places in your content.
7. Do not exceed 7% keyword to content.

Then submit different content with the keyword phrase to article websites to get back-links and do all the other SEO work – be sure to create a different version of the content to avoid Google counting it as duplicate content.  This article describes one effective method to get a higher search rank – you should always employ more than one method to achieve the best results.

There is a lot to SEO.  If you want to learn the ins and outs of SEO in detail, I suggest checking out SEO Book by Arron Wall - it is worth every cent.

If you are not familiar with HTML, then you may need some help with this.  In either case, here are some examples of what I am talking about.

Examples (HTML):

The title tag for the phrase “free weight loss exercise program” could be as follows (the red color is for emphasis):

<title>Free weight loss exercise program with tips and advice for losing weight.</title>

The Meta tags could look like this:

<meta name="description" content="This unique free weight loss exercise program is a proven system to lose weight and keep it off for good. Includes tips and advice from leading experts.">
<meta name="keywords" content="free weight loss exercise program, weight loss, fat loss, exercise">

The content could look like this:

<h1>Free Weight Loss Exercise Program Rocks The Pounds Off</h1>

<p>Loosing weight is difficult to say the least.  If you are looking for a <b>free weight loss exercise program</b>, you’ve come to the right place.  With this new free weight loss exercise program, you can not only lose weight, but you will keep it off and have more energy for enjoying life.  Most programs cost money, but this is a free weight loss exercise program for you to get started on the road to better health and vitality.</p>

(you would probably want more text in between your keyword phrases to make it more informative and easier to read – but this is just an example.)

And so on ... of course, as you go on, you don't have to use the keyword as frequently - that would make it annoing to the reader.