i hav that tuner...i also want an answer to your questions =)

You could just hold down on whatever fret corresponds to a note you can tune to. ie, hold the 4th fret to play an E on your c string.
for the high E (thin one) press the second fret and tune it down until that fretted note becomes an E. do that for all the other strings except for the low E (fat one) fret the 4th fret and down tune that string until it becomes an E. and there you go your know in drop C and if you didnt understand that too bad and visit here https://www.ultimate-guitar.com/forum/showthread.php?t=437340