Education.com has a great resource for this called SchoolFinder (located on one of the tabs above or on the link I entered below).  Enter the city ans state where you will be moving to and it will give you a list of schools you can contact.

You'll need to determine which School District your children will be attending school in to get the process started. The School District will inform you what grade your children will be attending, school start and stop times, transportation, etc. You can use http://www.education.com/schoolfinder to find schools that your children may be attending and then contact the officials at the appropriate districts. You can find the district's website with a Google search - they will generally have a Contact Us section in the left hand navigation bar. Additionally, some districts in Florida have websites available in Spanish and Portuguese (these links may be anywhere on the page).

Here are some of the requirements (birth certificate, medical exam, immunizations) for entry in Florida Public School:
http://www.fldoe.org/faq/default.asp?Dept=107&ID=966#Q966

If you cannot figure out your school district, contact the Department of Education in Florida for this information.