You can manually create and update your XML Sitemap, but it’s time-consuming and inefficient.
The process would be:
1. Create your store for the first time.
2. Manually create an XML sitemap.
3. Then in time you would modify your categories and products.
4. Then you would have to manually update the sitemap again.
5. The next time you modified your categories or products, you would have to manually update the sitemap as well.
To make the process easier, it can be automated by using a feed.
That process is:
1. Create the XML Sitemap Feed. See: To Create a Standard Sitemap Protocol Feed
2. Generate the XML Sitemap. See: To Create an XML Sitemap
3. View the XML Sitemap (optional). See: To View Your XML Sitemap
Once you have the above process created, your XML sitemap will be updated automatically.