I'm not 100% sure what you're asking but what you said above means whatever chord you said plus the next note after the slash as the root. Tell it to him that way. To explain that it means what note to play as root. For instance C/G being C chord with G (bass note) played on his 6th-string. Same thing with D/F#, it's just a D chord with F# at fret 2 on the sixth string. G/F is rather unusual. If you are wanting a G7 but you want F as the bass note, you'll have to tell him that, else, he'll just play a G7 chord with G note in the bass position.