How to download music to my iphone library with windows pc?

Ok so I've been trying to download music to my iTunes library on my iphone but I just don't know how. I also have a windows 8 pc. And whenever I click "download" it only downloads to my computers music library. Help! I've been using a youtube converter for the downloads, but all I need is to know how to transfer that to my iTunes library on my iphone.

Open iTunes and drag your downloaded songs into iTunes library, plug in your iPhone. On the left sidebar there should be your iPhone name (If you can't find the sidebar, go to iTunes menu bar, under View, select Show Sidebar), go to your iTunes playlist and drag the songs you want to your iPhone. For all of the songs, go to your iPhone music library, even if you don't have songs, and on the bottom there should be a blue-ish bar. There might be a box saying "Autofill from iTunes library" click that ONLY if you want All songs from your iTunes to your iPhone. For some youtube songs, they are copyright protected, iTunes can't upload the songs to your iPhone, you need some third party software to do that, I used to do that with this iOS file manager, worked well, hope it helps you.

Hi, it's easy to do this. Third-party programs like iPad Transfer Platinum(supports iPhone, iPad, iPod) http://www.ipad-video-converter.us/ipad-transfer/ allows you to move your songs downloaded on computer to your iPhone directly.