How do I create an Entity Relationship Diagram and a Use Case Diagram for the following system?

The pharmacy at Mercy Hospital fills medical prescriptions for all hospital patients and distributes these medications to the nurse stations responsible for the patients care. Prescriptions are written by doctors and sent to the pharmacy. A pharmacy technician re-views each prescription and sends it to the appropriate pharmacy station. Prescriptions for drugs that must be formulated (made on-site) are sent to the lab station, prescriptions for off-the-shelf drugs are sent to the shelving station, and prescriptions for narcotics are sent to the secure station. At each station, a pharma-cist reviews the order, checks the patients file to deter-mine the appropriateness of the prescription, and fills the order if the dosage is at a safe level and it will not negatively interact with the other medications or aller-gies indicated in the patients file. If the pharmacist does not fill the order, the prescribing doctor is con-tacted to discuss the situation. In this case, the order may ultimately be filled, or the doctor may write an-other prescription depending on the outcome of the discussion. Once filled, a prescription label is gener-ated listing the patients name, the drug type and dos-age, an expiration date, and any special instructions. The label is placed on the drug container, and the order is sent to the appropriate nurse station. The pa-tients admission number, the drug type and amount dispensed, and the cost of the prescription are then sent to the Billing department.