Can I use the Services module without coding skills?
Using migrate and services are for separate use cases IMO. 

I'd use Migrate for a one-off or periodic import and use Services for RESTfully add/update/deleting one at a time. 

The services module includes integration with the user module and you can pretty much administer/point and click to get an xmlrpc endpoint with the user resources added. 

You'd have to write a bit of code on the first site though, you might use a user hook http://api.drupal.org/api/drupal/modules!user!user.api.php/function/hook_user_insert/7 (or update, delete etc) and then use the data to make a http request to your other site http://api.drupal.org/api/drupal/includes%21common.inc/function/drupal_http_request/7