It may be hard to find a bike driving school, but i guess these r your options:
1) Force a motor driving school to teach you bike.
2) Its not bad to acknowledge, even in public that you don't know to drive. Its not your fault that u didn't get any chance. Ask any good frnd(or make one.. bribe him..buy him a drink) to teach you how to drive.
If you were adventurous with cycle, its gonna be very easy with bike.
I suggest you start with gearless stuff (give compliments to a girl, bribe her with some gift in leu of teaching u scooty. In the end, with the driving skill, you may even have the girl).
I used to drive ranger in my childhood. Then i graduated to scooty(borrowed- offcourse) and it took me few seconds to gain control. Then i was afraid of geared vehicle.. so i bought mine a year ago and asked a frnd to teach me on light traffic road. In a week, i was ready to go.. driving at 100 kmph on highway

.. and yeah in 1 year.. i have proved 2 be a decent driver.. with no black track record, no mamu panga.