I need to adjust a Casio AMW320rd-1A9 STA...

This band is put together with cotter pins. To remove the cotter pins look at the edge of the band. The end of the pin that comes out is split and looks like a screw. The end that is solid is the end you want to push from. Use a small punch to push the pin out. The split end is the bigger end of the cotter pin so it needs to come out and go back in the same way it came out. Make sure you remove an even number of links on each side so the watch sits on the wrist the right way. You also have a micro adjustment on the clasp. To adjust the clasp simply use a punch to press the spring bar in the clasp in until it moves. This is a spring bar so be careful it doesnt jump out if the clasp comes apart.