Creating PSCredential Objects
# username and password
$userName = 'user'
$userPassword = 'pass'
# Convert passwird to SecureString
$secStringPassword = ConvertTo-SecureString $userPassword -AsPlainText -Force
# Create PSCredential Object
$credObject = New-Object System.Management.Automation.PSCredential ($userName, $secStringPassword)
Oneliner
$credObject = New-Object System.Management.Automation.PSCredential ('username', (ConvertTo-SecureString 'password' -AsPlainText -Force))