I cant access my webpage internally in the entwork

Ok the problem is that when you use xyz.com you're calling your domain as well. And this is used for troubleshooting the domain, for example, pinging xyz.com will make the "domain" to answer instead of the Webpage.

Solution1:
You can add an "A" record on a registry with the hostname @ and the internal IP of the web server.
Solution2
it's to use the www always ( create an "A" record with the hostname of "www" and add the binding into the IIS as www.xyz.com)
that's another solution.

is any record or way to add in the DNS to display my website in all the computer even if then put www or not?

I'm afraid not. If your internal and external domains have the same name, you'll always have to add the www to the URL in order to access the site internally. Your AD domain controllers register DNS records internally that cause the FQDN xyz.com to resolve to the IP addresses of those DCs. Those particular DNS records are essentially obsolete nowadays, as they are intended to allow non-site-aware systems to locate a domain controller. (In a Windows context, "non-site-aware systems" translates to "operating systems older than Windows 2000," but it may also apply to non-Windows OSes.) If you delete them, though, they'll just come back; the DCs will re-register them. If you create your own blank host record, your internal clients may or may not resolve it to the address of your website each time they try, because of the way round robin DNS works.

I'm sure there's a way to prevent the DCs from registering those particular DNS records while still allowing them to register all of the other ones. It's also possible in most cases to rename your internal domain. However, I don't think either of these things is worth the effort. We're taking about a character string consisting of three w's and a dot; it's not that hard to type. :)

Sorry I didn't mention my web server is not in my internal network is in a cloud service

A hack I do not recommend is to run a web server on the domain controller, performing a HTTP redirect to www.
You can also use a port proxy/port forwarder on the DC for HTTP(s), which is a low-profile workaround, not adding to vulnerabilities, and hence sounds better. FPipe is one of those.

In the long run, you will want to change the name. Something like ABC.xyz.com (can be any unused subdomain).