How do you structure a written product description?

I'm writing the product description for the business plan of my website and I'm looking for a proven structural template.
My website is a mircodonation service (see my profile if your interested). The examples I can find via google are mainly for physical products or are just long texts which don't really offer any structre.

EDIT

This what I've come up with so far:

First a High-Level Overview (but more detailed than the exec summary), which answers the question like Jarie suggested.
Then I created a use case diagram, which shows all the relevant use cases. I then describe all use cases using bullet points.
Finaly I created a chapter describing the technologies and services used.

You might want to take a look at this canon answer on how to define a product for some hints.

For any product, you need to answer the following questions:

• What does it do?
• How does it do it?
• What customer pain does it cure?
• How much will it cost?

If you can answer those 4 questions, you are in good shape.

In terms of a template, it really depends on the product and the audience. My preference is nice headings with bullet points of key features. That way, it's easy to skim.

Why not post it and get feedback.

The structure is being able to say it in a single sentence or two.