What are the laws regarding a child riding a motorcycle in Florida?

Seat Belts

Anyone riding in the front seat of a car built after 1968 must wear a seat belt. (The threshold is 1972 for trucks.)
However, if you're under 18, you must be protected by either a seat belt or an appropriate restraint device no matter where you're sitting.
If a passenger under 18 violates this law, the driver will be held responsible. After that age, each passenger is held accountable. Violators will be fined at least $30 for the offense, plus court costs.  

Child Safety Seats

Passengers under the age of five need to be secured in a government-approved child restraint or safety seat. Children under three years old must be seated in either an approved infant carrier or child safety seat.
If you're in the market for one, you can shop online for a child car seat at any time. When ordering, be sure the car seat matches your child's height, weight and age.
Note: Children should always be placed in the back seat, as it offers the most protection in a crash, and also avoids dangers associated with front-seat air bags.  

Headlights

Headlights must be turned on between sunset and sunrise, and during periods of rain or fog.  

Cell Phones and Texting

Florida doesn't impose any statewide restrictions on cell phone use while driving a vehicle. This also applies to texting.  

Helmets

If you're at least 21 years old and have a minimum medical insurance policy of $10,000, you can bypass wearing a helmet while riding a motorcycle.
However, all riders must have some sort of eye protection, such as goggles or glasses, or have a windshield on the bike.

Reporting Unsafe Drivers

Anyone spotting a driver who is driving suspiciously or dangerously can dial *347 (*FHP) at no charge on a cell phone to report the situation to the Florida Highway Patrol.
You can also call this number to report an accident, or a disabled vehicle.  

Unattended Children

If you're supervising a child under the age of six, you're legally allowed to leave the child unattended in a vehicle for a maximum of 15 minutes.
However, you cannot leave the child unattended for any period of time if the vehicle is running, or if doing so places the child's health or safety in danger (such as on hot days).
Law enforcements officers may do whatever is necessary to free an unattended child from a vehicle when the situation warrants it.
Anyone violating these laws can be charged with a noncriminal traffic infraction, and face a fine of anywhere between $50-$500, depending on the circumstances of the offense.
Hope this helped ! ;)