Kind of a broad question. Let's deal with it in parts.
If you are under 21, it is unlawful in the State of Ohio (with a few explicit exceptions) for anyone to provide you a handgun. So, if you were planning on carrying, how are you going to get the gun?
No one may carry in a car without a license, regardless of age.
Now, if your friend is a "responsible adult" (whatever that means) and can lawfully carry the gun, he may take it and you to the range, and provide you the handgun for training purposes.