In order to submit your sitemap, you must first verify your website in Google. Follow this article to learn how to do this.
Step 1. Log in to Google Webmasters Tools and select your site on your Google Search Console home page
Step 2. Click ADD/TEST SITEMAP
Step 3. In the text field next to your domain, type sitemap.xml and click Submit.
Note: Do not enter any additional text. For example, do not enter the page name.
Step 4. Refresh the page to view your website on the list.