Photo taken from dinqua's site. This is the view with the carbs removed looking up at them. They can be found with the carbs installed just adjacent to the carb heater wire connections on the carbs each side on the front of the carbs on the bottom.
Its possible depending on what year your bike was made and in what time frame of that year that there could be tamper caps in them. My 04 had these and it was necessary to take a small very small sheet metal screw and gently so gently tap it into the tamper cover unitl a few threads were engaged and then grab with a pliers and wiggle the caps out. Once the caps are off a small flathead screwdriver of an appropriate size is used to turn the screw in and out. If yours is a later model it will not have the covers on the mixture screws but you will need a "D" tool to adjust them.
Once again full detailed info can be found in the tech vault in Dinquas site.