Here's an example of how to import the PowerShell command set, login and then logout.

PS C:\> Import-Module "C:\Compellent.ApiCommandSet.dll"

$pass = ConvertTo-SecureString "Password" -AsPlainText -Force
$conn = Connect-ApiConnection -Host "localhost" -Port 3033 -User "User" -password $pass

Disconnect-ApiConnection -Connection $conn