Q: How do I change my Apple ID on my iCloud?

I've been an iPhone user for years now and always had the same email and apple id. However, recently I had issues with my email address and decided to change my apple id to a new email. I changed my email and apple id and got it synced with my iphone and itunes account. How do I update my icloud to the new apple id and email? And how do i do it without losing what i currently have saved to my icloud now? Thank you for any help.