$SPWebURL = “http://SP2013/sites/SiteCollA”
$MylibraryName = “MyDocumentLib”
$MyFilePath = “C:\file.docx”
$SPWeb = Get-SPWeb $SPWebURL
$List = $SPWeb.GetFolder($MylibraryName)
$Files = $List.Files
$FileName = $MyFilePath.Substring($MyFilePath.LastIndexOf("\")+1)
$File= Get-ChildItem $MyFilePath
$Files.Add($MylibraryName +"/" + $FileName,$File.OpenRead(),$false)
$SPweb.Dispose()