Hi Benny. You have asked a good question. To transpose the alto sax part so that it sounds the same when played on the tenor sax your transpose each note up a perfect 4th. In addition you either drop a sharp from the key signature OR if there are no sharps to drop you add a flat. The theory behind this is that the Eb alto sax transposes up a 6th from concert pitch. So for example a middle C on the piano becomes a written 2nd space A for alto. The same middle C transposes up a 9th (an octave and a whole step) to a 4th line D for the tenor. D is the 4th tone of the A scale so it is said to be a perfect 4th higher. You don't really need to worry about the perfect 4th thing right now as long as you just go up 4 notes and make sure to change the key signature as listed above. The alto sax remember transposes up a 6th from concert pitch and the french horn transposes up a 5th. I am going to let you figure out the rest. When going from alto sax to horn the key signature will drop 2 sharps or add 2 flats OR drop 1 sharp if there is only one and add just 1 flat. Good luck. John