This is a big undertaking. I have planned and participated in many school carnivals over the years. Hopefully, someone has some experience doing this. There is a lot of information on line that might help http://www.ehow.com/how_###-###-####_plan-elementary-scho...
First you need to have someone to head this up and then reliable volunteers to fill the major roles (games, food, publicity, safety/security, silent auctions/volunteer recruiter, etc, etc. If you are asking specifically about getting donations - first, you may need a letter on school or PTA letterhead (ask the principal what the district requires) requesting donations for your event. Include your 501c3 number or the tax id number for the school. Most Businesses will want an official letter for donations. Send out a letter or email to all parents for donations - perhaps they have a company or know of a company that may make a donation. Then make a list of all of the restaurants and stores and services (banks, insurance agents, etc) that your parents shop at in the area. Contact them - in some areas, letters will work; in other areas, personal contact is required and would get you better results. Some companies are allowed to make decisions locally, some require a letter to corporate or filling out an online form to request a donation. Ask! Go on line and see if there is a form required. Don't forget about parents who sell Mary Kay, or Avon, or Advocare - they may be able to make you a gift basket to put in your auction. Other ideas are: Clear this with the principal - ask each teacher or grade level to make up a theme basket. Perhaps the room mothers might help out --(books, arts & crafts, school spirit items, stickers, toy trucks - if half the class brings an item to donate on a theme you will get some attractive baskets). I have seen class artwork projects are very successful at raising funds for schools - parents will often try to outbid each other. Those are just a few ideas. Who will donate? Chick Fil A will often give coupons for free food items (if you are in their area), WalMart stores used to have some local discretion for gift cards for local schools (not positive about current policy because they also have a website to request donations) I don't want to discourage you because I know that new schools have tremendous needs, but it is now Fall. If a lot of planning has not already been done for this event, I would consider holding it in the spring or postponing to year #2. Good luck --if takes a lot of people to make this work, but it can be a fun event for your school community and raise a lot of money.