1. While logged into the Admin tool
  2. Expand the top level "Organization" node from the tree-view on the left hand side
  3. Expand the specific Organization that you want to add the user to
  4. Expand the "Organization Users" node
  5. RT Click on the "Users" folder
  6. Choose "Add Users" from the context menu
  7. Once the "Add Users" Dialog displays select the user you wish to add to the organization under the "Available Users" list
  8. Click the "OK" button at the bottom of the screen