Classic/Antique Car Repair: tighten transmission bands?, chevy bel air, turn of the wrench

Question
i have a 61 chevy bel air 6 cylinder. the transmission slips when i get to about 30 mph. people keep telling me that the bands need tightening but they don't tell me how to do it. how would i go about tightening these bands?

Answer
Shawn;
Hi well what I would do as this is not a simple turn of the wrench.  I would go to one of those tranny shops when they have the 25.00 special check up. you might need a new filter/screen and some adj. on the inside or parts. or  bu tring to adj. it yourself could run into a few 100. or more