Is it possible to share songs from itunes on a Windows machine with apple music on an iphone?

Yes. 2 ways.

1. If subscribed to the Apple Music subscription service, you can use iCloud Music library to make your music from the Windows PC available to the iPhone. See here: link-> Use iCloud Music Library on PC - Apple Support

2 . You can connect the iPhone via a USB cable and sync the music from iTunes directly onto the iPhone. See here: link-> Use iTunes to sync your iPhone, iPad, or iPod with your computer - Apple Support