Install iTunes on your PC - Create your playlists and then sync to iphone. https://support.apple.com/en-gb/HT201253 I tend to sync 'Selected playlists' rather than the Entire Music Library.
Or....if you don't want to trust the computer/phone to do what you want, try dragging and dropping the tracks/albums that you want on your phone. You do have to install iTunes first on your PC. Once that is done the PC will recognise that you have attached your phone via USB. Then it is easy just to drag what you want onto the phone icon that you can see in iTunes. I do it regularly. Works for me.