How to specific OU automatticaly for new user in AD? - powershell

Question

Import-Module ActiveDirectory
$firstname = Read-Host -Prompt "Please write firstname"
$lastname = Read-Host -Prompt "Please write lastname"
$SearchBase = "DC=Domain,DC=com"
$OUList = Get-ADOrganizationalUnit -SearchBase $SearchBase -Filter * -Properties Name,DistinguishedName | Select-Object -Property Name,DistinguishedName
$OU = $OUList | Out-GridView -Title "Select OU and Click OK" -OutputMode Single
#Create the AD User
New-ADUser `
-Name "$firstname $lastname" `
-GivenName $firstname `
-Surname $lastname `
-UserPrincipalName "$firstname.$lastname".ToLower() `
-AccountPassword (ConvertTo-SecureString "Customs1!" -AsPlainText -Force) `
-Path $OU `
-ChangePasswordAtLogon 1 `
-Enabled 1 `
-DisplayName "$firstname $lastname" `
-SamAccountName "$firstname.$lastname".ToLower()
$timer = [diagnostics.stopwatch]::startnew()
$erroractionpreference = "silentlycontinue"
$mailboxsuccess = $false
while (($timer.elapsed.totalseconds -lt 900) -and (!($mailboxsuccess)))
{
$error.clear()
Enable-Mailbox -Identity $username -Alias $username -Database $mailboxdatabase
`your text`
if($error.count -eq 0)
{
write-host "Mailbox successfully created"
$mailboxsuccess = $true
}
else
{
write-host "." -nonewline
start-sleep -s 30
}
}
$timer.stop()
$erroractionpreference = "continue"
$secs = "{0:N2}" -f ($timer.elapsed.totalseconds)
write-host "Process ran for: $secs seconds."
I try to create an user in specific OU automatically with grid table where I select an OU and click ok, but my program doesn't work, after run appear this.
Please write firstname: Test1
Please write lastname: Test2
....
I need help, thank you.
So far I managed to create a user in a specific OU manually, but I don't want this, I want in automatically mode, I don't know how...