A "jammed" finger is a basically a sprain of the finger. A sprain is an injury
that occurs when the ligaments that hold the bones in the fingers and hand together become stretched or, in severe cases, torn. This leads to pain, swelling, and stiffness.
Sometimes, a more serious tendon injury or broken bone may also occur as a result of jamming the finger, and so it is always important to have your regular sports medicine or primary care doctor
take a look to figure out the extent of the injury.
Importantly, there is no quick way to heal a sprain. Typically a sprain will require rest and splinting, along with ice and anti inflammatory medications. Healing will take at least several days for the worst pain and swelling to go down, and most people have symptoms for weeks.
I would highly recommend that you talk with your doctor to determine whether it is safe for you to play foot ball right now. I suspect that it will not be safe for you to play, especially if the sprain is severe, because of the risk that you could injure the finger even more. However, your doctor will be able to help you make this call.