Doctors and surgeries can be added/updated when creating or updating a patient record.
Adding Doctor/Surgery to a Patient
Next to the Surgery field, click on the Select Surgery button.
This will open the Assign Doctor & Surgery window. From here you can select an existing surgery from a list of surgeries (1), search your list of surgeries (2), or create a new surgery (3).
After you have created and/or chosen your desired surgery, you will be prompted to create or select a doctor from that surgery. You do not have to choose a doctor and can just have a surgery assigned to the patient, however you cannot assign a doctor without first assigning a surgery.
Once you have finished selecting, click Save to confirm your choice and then click Save again on the patient record to update.