Function Set-WallPaper($Value){
    $url = "https://memeoftheday.ping-mee.de/wallpaper.png";
    $wc = New-Object System.Net.WebClient
    $wc.DownloadFile($url, "C:\temp\wallpaper.png")
    Invoke-WebRequest $url -OutFile C:\temp\wallpaper.png
    Set-ItemProperty -path 'HKCU:\Control Panel\Desktop\' -name wallpaper -value $value
    rundll32.exe user32.dll, UpdatePerUserSystemParameters
}

Set-WallPaper -value "C:\temp\wallpaper.png"