How can i add cooling fan in series or parallel with a led diode
The fan will want a constant voltage supply of 12V.  While it's possible you could just stick the fan in parallel with the LED and it would work okay, you would be stealing a bit of current from the LED and if the LED ever became open circuit, even for a moment, your fan would likely be destroyed because the open-circuit voltage of the CC driver would be much higher than the normal operating voltage. 

So your best solution is a separate constant voltage 12V supply that can supply the required current. Most likely it will be capable of a lot more than 90mA, but that's not a problem provided you are within the minimum current spec of the supply (usually 0mA to 10% of the maximum current). 



Edit: Possible protection to use one supply: 

This will protect the fan up to about 55V with R2 a 5W resistor. 







simulate this circuit &ndash; Schematic created using CircuitLab