In order to transfer the music to your iPad library, you will need to download and install iTunes, because you can't do it directly through your Downloader tool. Once you launch iTunes navigate to File > Add File to Library/Add Folder to Library, navigate to the Downloader directory, select the desired music files or the folder containing the files and press the Open button. After that, connect your iPad to your computer, launch iTunes and select the device from the Devices list. Click the Music tab, check the Sync Music box and select Entire Music Library or Selected playlists, artists, albums, and genres. Follow the on-screen instruction and click the Apply button to start the transferring process. Also, you can transfer the music manually if you enable the Manually Manage Music and Videos option from the Summary menu. Once you enable this feature, drag and drop the songs you want to transfer from the Library to your iPad's name.