How to use the Onboard clock on my PCI-DIO-32-HS to get desired time difference between successive digital output to the ports

How to use the Onboard clock on my PCI-DIO-32-HS to get desired time difference
between successive digital output to the ports.
Desired operation is as follows,
time(s)             data
t=0               data0
t=2e-6         data1
t=1e-5         data2

and so on....

As the time difference between successive data out is in microseconds i cannot
use software timing(as it is generally in millisecond). and also the time
difference between every successive data isn't constant so i need to write a
wait function which uses something like "WaitForNextSampleClockPulse" to get me
exact time lag between successive data-out with jitter in nano seconds as
onboard clock is 20MHZ.

I want to write a C program and link the DLL to the operating VI.
I am having trouble understanding how to use the Onboard clock to get it done.

Thank you!
Software Details: ANSI C (Visual Studios) (Free form entry)  version
NI Hardware:  PCI DIO 32 HS 
Driver Version :  
Operating System:  Windows 7