Need to change Apple ID

You cannot use @me.com, @icloud.com & @mac.com as your only e-mail address.

What you need is a valid e-mail address and register it as your Apple ID.

Note: All content are forever tied to the Apple ID used to obtain them.

Content cannot be merged or transferred to another Apple ID.

Use this link: https://appleid.apple.com.

Also read here: Change your Apple ID - Apple Support

If your Apple ID is just an iCloud account, then that's is going to be problematic.

You'll need to contact Apple Support directly and sort it out with them. You cannot change the "name" part of an iCloud account yourself.

https://www.apple.com/support/icloud/contact/