You can present your white paper online, in print, or a combination of the two. One option is to write the full white paper for use online, making full use of hyperlinks to provide the reader with instant access to supplemental information, then write a shorter "highlights" version for print. In this way you can provide a personal touch, sending out your "highlights" white paper along with a tailored note to the person requesting it. A simple indication of where to find the rest of the information online will get your point across without overwhelming your readers or your budget with huge printouts.
Whether you use one version or two, all white papers should contain some key elements, including the problem as you see it. Your perspective here will frame or even create the need your product will solve. Make it clear that this problem deserves serious attention. Also state how you perceive the status quo. Explain the steps that other companies are taking to solve this problem, if any. Don't be afraid to acknowledge success, but pave the way for yours to be the superior option. Then make sure that you include the solution. Explain how your company's product solves the problem as described. Include a look toward the future, showing how your company will maintain and/or adapt its solution as necessary to meet upcoming challenges.
Beyond these basics (other than using standard-sized paper for the hard copy version and/or using PDF format for the online version in PDF format), there are no real rules for white papers. Use your target audience as your guide for how to state your case compellingly. In any case, visuals are often good additions to a white paper.
For a general overview of structural elements to include in a white paper, along with a generic outline, click here.