Hi. If you register a domain and you call it www.KarlaKarla.com for example and then I get married and change my last name and want that name reflected in my domain name and want to change the last name that I put in my domain, could I do that, and keep the website as it is, just change the URL?
It can be done. It depends how your site is built as to how to accomplish it, but yes it can be done. Are you using wordpress or something else? Basically you would register the new domain, and then make some changes to switch over to it. You will probably also want to keep the old domain name and re-direct it to the new domain name.
I have not created a website yet, but I would use wordpress.org.