cannot create ID @icloud.com

Sorry, not clear on what you mean? If you are logging into iCloud, then you already have an iCloud.com email address associated with your Apple account. You can see what the address is by going to Apple - My Apple ID on your computer and check to see what your iCloud.com email address is.

Best,

GB

You need to sign out from iCloud account and then create a new Apple ID ending with iCloud.com

See this link https://discussions.apple.com/docs/DOC-13681

And up coming steps .

( f ) Click on create Apple ID , the circle rotates , your date of birth is used to determine which services to set up on this Mac .

( 1 ) Date of birth - Day [ ] , Month [ ] , Year [ ] , click on drop down arrows of day , month , year and fill up the credentials and click on next .

( g ) A window appears get started with your name , email address and password 

    Name [ First ] [ Last ]

    Email address - name@example.com

    This will be your new Apple ID 

    Get a free iCloud email address 

    Password required …….

    Verify ……..

Your password must be at least 8 characters long & include a number , an uppercase letter and a lower case letter .Fill up the credentials .

Check the box of apple news and announcements …..the terms and conditions and click on next .

Enter a phone number which can be used to verify identity via text message or phone call 

Phone number …….country code will be written .

Phone number ……… enter your trusted mobile number .

Verify with - text message , phone call its optional you can check the box for text message and fill up the credentials it will show .

Did not receive code , cancel , next .So click on next .

( h ) Terms and conditions - check the box of license agreement and click on agree , a circle will rotate a prompt will appear to enter your password for admin , so enter the admin password correctly and click on ok .

( I ) A window will appear .

   Use iCloud for your documents and data .

   Use find my Mac 

   The boxes for them are checked by default , then click on next .

( j ) Again , a window will appear allow find my Mac to use the location of this Mac ?

   Not now , allow , you have to click on allow .

You are signed with new apple id and password , check the box for Siri , wait for while after few minutes you will be able to move your cursor , click on iCloud Drive option button and check the box of documents and desktop .