How can I make iCloud account?

Go to: http://appleid.apple.com

Then click on Create your Apple ID at the top right corner of the page (next to Sign in).

You are sign in here . . . .

Your Apple ID is the personal account you use with all Apple products and services. It includes the email address and password you use to sign in, as well as the contact, payment, and security details that you use with Apple.

You can’t merge multiple Apple ID accounts.

See also this Apple article: Sign in with your Apple ID

Sign in with your Apple ID - Apple Support