How can I pass domain admin credentials in powershell to create users?

I would like to have my HR department create user accounts for new employees. In vbscript I could do something like 

Const ADS_SECURE_AUTHENTICATION = 1

Set ou_SES = DirectoryService.OpenDSObject ("LDAP://OU=Elementary,OU=Students,OU=Sidney Central School Network Users,DC=sidney,DC=k12,DC=ny,DC=us","administrator","password",ADS_SECURE_AUTHENTICATION)

How can I pass the admin username/password in PowerShell? My plan was to hard code it in and then encript the script.

Thank you