Q: How do I move my music from I-Phone 6S to I-cloud, to free up Gig sapce

You would need to join Apple Music, then enable "iCloud Music Library", then let your iTunes library upload to iCloud (which can take a looooong time depending on your internet speed and size of your library).  If you have an iTunes library on your computer, do these things on the computer first, then enable these settings on your iPhone.  But keep in mind that it may take days, maybe even a week, for the iCloud library and your device library to "stabilize" such that your device sees any change in available capacity.  iOS should manage what remains on the device, but expect that it won't be an instantaneous gain in capacity.

More info:

Check your Apple Music library settings - Apple Support