The planning wizard makes it a snap to get started since you simply answer yes or no questions to create your custom business plan framework. Bplans.com offers free business plan samples and how-to articles as well as a wealth of other information. It is definitely worth taking the time to checkout. Microsoft Office Online Templates also has a variety of free templates to use with their products. The wizard indicates the information you need and you fill it in as you go.
At this point, you may be tempted to skip writing a business plan altogether, viewing it as an unnecessary exercise in jumping-through-the-hoops, suggested by some old business professor who probably never held down a "real" job anyway.
But your idea may be so new that you may also need to talk to potential customers, host some focus groups, talk to an ad agency, or maybe even make a prototype and float it past some people. Be prepared to spend the time. Remember, it's not about the Plan but the Planning.
Are there emerging markets or market segments? Where does this product or service currently perform best? Possible Data Sources: trade associations; trade journals; attorneys & accountants dealing with the industry; industry salespeople; state business websites; focus groups.