To grant a user access to the Hosted SharePoint site:
- Click "Site Actions" and select "Site Permissions".
- Click "Grant" and select "Grant Permissions".
- Enter the user in the format "alias_organisation" and then click the icon. Note that "alias" is the part before '@' in the username and "organisation" is the name before '.hostedsharepoint.co.nz' in the URL.
- Select the appropriate permission level.
- Click "OK".
For more information on default permission levels and user permissions in SharePoint Foundation 2010, please refer to http://technet.microsoft.com/en-us/library/cc288074(v=office.14).aspx