Assuming this not a life or death emergency, first I would tell my supervisor or lead that I had suffered a work injury. If there is a process in place to document work place injuries and accidents such as an Accident Form or Incident form have you supervisor or lead fill one of those out. Typically witnesses will be documented in this accident or incident form and then you will sign and date the and then your supervisor will sign and date the form.
The next step will be to seek medical treatment. Again assuming this is not a life or death emergency, you might decide to forgo a traditional ER and either go to an urgent care or walk-in clinic where the provider charges a flat fee. Why would you want to do that. Well if your claim is allowed, then ER charges would be submitted against your claim. If not better to be stuck with a couple hundred dollar charge, rather than however many thousands an ER visit may cost you. You may also choose to go to your Primary Care Physician. The whole purpose of this initial medical visit is to take care of your injury, and DOCUMENT your work injury and body parts that were injured.
Finally, you will want to submit a FIRST REPORT OF INJURY form or FROI-1. Typically if you go to an ER or Urgent Care they will ask if your injury is a work injury or not. If it is a work injury they will fill out a FROI-1 form and send it to the BWC. This will start the BWC claim process. You can submit an FROI-1 form yourself without a medical provider signing and dating it as well, however you will still need to have a medical provider relate your injury and injured body parts to your work activity.