My friend died from carbon monoxide poisoning yesterday. How do i experience closure? I'm only in high school.?

One of my best friends tragically died from carbon monoxide poisoning yesterday. I'm having a terrible time trying to heal. I know it's been one day but I feel like I have a huge hole in me. She was such a good friend and I just feel so sad when I think about her. I'm seventeen and she was sixteen and it's just hard losing a friend at this age. How do I get closure?