How do I add a sitemap to my site?+issues

I generated one and uploaded it as a card. I know you guys said the site doesn't really rename files, but google can't find the file I uploaded unless I give it the renamed filename with the numbers in it. I don't know if that actually matters in whether or not it will serve its purpose once I give google the URL. But... shouldn't I be able to sitemap.xml on my site AS sitemap.xml somehow?