To receive all link juice to one place it’s better to have only one version of your website address: either www.domain.com or just domain.com
Here is the simple instruction how to make 301 redirect from www to non-www (or vise verse).
1. Find .htaccess file (search for it with FTP). Or if you don’t have it (this may be the case with simple HTML websites) – than Download this 301 redirect example .htaccess file
2. Open it with a program such as Notepad
3. Edit it changing domain.com to your own website and press “save”
4. Upload the file to your website via FTP
5. That’s it! Now check if it worked by accessing your website with www
Don’t forget to check all other webpages to be non-www too!