how do i get a free government grant to start a business

Contact the US Small Business Administration for information on government grants and financial assistance for small businesses. Since you probably need basic advice on working with the SBA, go to this link for more information:
http://www.sba.gov/financialassistance/borrowers/resources/basics/index.html

You may also want to contact the Florida Small Business Development Center. You can find the nearest location to you by going to the following link:
http://floridasbdc.org/Home/Location.asp

Of course, as with all of my online answers, my advice is limited by the brevity of your question and the facts provided. Additional information would be required to provide definitive legal advice, so this answer isn't intended to, and does not, create an attorney-client relationship.

Good luck!

There are a variety of resource guide and associations that you should consult. To start you off I have included two below. While Crains is more NY centric, it has a wealth of small biz resources including grants. There are likely FL centric biz publication as well that have similar guides.

Secondly, you should see what kind of trade and/or bizdev associations might fit you and your product's niche. For example, I am Asian American and the Asian American Business Development Center can point me in the direction of bizdev resources (including funding) that might be of assistance. Perhaps you and/or your product speak to a particular association that can take interest and assist you.

I hope this helps.

Disclaimer: This answer is for informational purposes only and does not constitute general or specific legal advice, nor create an attorney client relationship.