The HIGH command makes a pin
The HIGH command makes a pin high. So HIGH 8 and HIGH 9 would make those PWM pins high. To make it run for a period of time, have it in a loop combined with PAUSE to get however long wanted. Below will have pins 8 and 9 high for 1 second (200 x 5 ms) before setting them low again.
count VAR Byte
Setup:
LOW 8
LOW 9
Main:
FOR count = 1 TO 200
HIGH 8
HIGH 9
PAUSE 5
NEXT
LOW 8
LOW 9
END