Name order on CMS's add user block
You can update the profile that is being used for registration by changing the weight of the field or using top/bottom arrows to change the order how they appear.

Navigate to Administer >> Customize Data and screens >> Profiles

Check the profile used for Drupal Registration and then click on the fields link besides it



Use the arrow button to change the order of the field.



You can also change the weight of the field by clicking on edit link of the field and then changing the order.



HTH

Pradeep