I'm sorry for your loss. To request bereavement leave, you can write a formal and polite email or letter to your company's human resources department or your supervisor. You may need to include the name of your loved one, the date or place of their passing and the relationship they had to you. It is important to request leave as soon as possible. You can also consider leaving yourself some time before returning to work.
I hope this helps. Let me know if you have any other questions.