Non Profit Business Plan

I recently became treasurer of a local trade group and have been appointed to develop an annual budget. I enjoy this type of challenge, but i’m definitely NOT a CPA. I’m hoping to find a series of web pages, books, or some actual examples of how to develop a pro forma. I want to build a formal one, and then use it to distill it down to an executive summary that various chairpeople can consult when they need an understanding of our business plan, our cash flow, etc. Can you recommend a good place to get started? I not only want to do a good job on this, I also want to really surprise people with the quality of it. Thanks!