To find a non-profit to review, doing a Google search is a good start. Try searching for 'non-profits in N.C.' for something local. You may also want to try searching for 'Charity Navigator', which will allow you to find a local non-profit agency.
A Google search for 'non-profits in the us' gives good results as well. Using the term 'charities' may also lead to good results.
The N.C. Center for Non-Profits has lists of non-profit organizations and how to categorize them. The title of the organization is a link to more information.
Top 100 Nonprofit Organizations has a list of organizations working all over the U.S. Take the list with a grain of salt and focus not on the ranking, but on the names of the organizations. This list will allow you to do further research on the non-profit's website.
http://topnonprofits.com/lists/best-nonprofits-on-the-web/
Forbes.com has a good list as well.
http://www.forbes.com/top-charities/
Charity Navigator enables a search for local non-profits. Search for your home town or a city in your area and see a list of non-profits.
These websites will let you know that the charity is registered and where the money collected is used.