Look for a first aider!
The form "Unfallanzeige" has to be filled out. Without the form the statutory accident insurance will not pay the costs. Ask for help in the secretariat of your group!
An entry in the first aid logs is needed. This serves to prove that the accident happened during work hours. If later on a medical treatment is yet needed this fact is documented and can be forwarded to the statutory accident insurance. For the entries ask a first aider for details.