Here is the link to google search console – https://www.google.com/webmasters/
Google wants you to add both www and non-www URLs to google search console and then tell them which one is the preferred URL. The preferred URL is the one where your site goes. For example, my site goes to https://gritsdesign.com – non-www – so non-www is my preferred version. Here is a screenshot of how you can set the preferred URL in google search conole – https://snag.gy/gOl5GM.jpg
If you have an SSL certificate, then you would add FOUR urls to google search console–https www and non-www and http www and non-www
Once the preferred version is set, you will only use this one to index your site. For example, if your preferred version is www and you do not have an ssl certificate, then you would ONLY use this url in google search console – http://www.yourdomain.com. If your preferred version is non-www and you have an ssl certificate, then you would use this url in google search console – https://yourdomain.com
You need to add a sitemap to your preferred version. Here is a screenshot how to add a sitemap – https://snag.gy/XeE8R4.jpg
You also need to index your preferred URL for desktop and mobile – see screenshot – https://snag.gy/HLe84t.jpg
You can do the same for individual posts – new and updated ones – use FETCH AND RENDER for individual posts – https://snag.gy/IUr3j0.jpg
Hope this helps!