When you put your domain.com in the address bar, there will not redirect to a secure SSL link as the default. Web Browser also will show your URL as not secure.
To fix this issue, you have to install SSL first. After that, place a .htaccess redirection via cPanel easy.
cPanel > Redirect.
After that do the settings as the below image.
(cpanel.lk domain is our domain name. use your domain instead of cpanel.lk)
Everything is done after "Add". Finally clear browser cache and try. You will be redirected to https://www.yourdomain.com