$Dir="C:\Users\xxx\Desktop\"
$file = "TEST.txt"
$fn = "test.txt"
#ftp server
$ftp = "ftp://xxxx/"
$user = "x"
$pass = "xxx"
$webclient = New-Object System.Net.WebClient
$webclient.Credentials = New-Object System.Net.NetworkCredential($user,$pass)

foreach($item in (dir $Dir $file)) {
    $uri = New-Object System.Uri($ftp+$item.Name)
    $webclient.UploadFile($uri, $item.FullName)
}