Accessing REST API with PowerShell - Get Method

Accessing REST API with PowerShell - Get Method

Hello everyone, 
Ive been following the instruction on the REST API and have done the following....
Created an API user account. 
Generated an SSH key. 
set key to not expire.

when using powershell , I am using the following line..


but on the return I only get the following....

operation
---------
@{name=Authentication; result=}


What is it that I am missing here??  
Do I need to include the API user account in the request?  or is the authtoken key enough??

Thanks