Well...volts frying? I can't say for sure. With LM317 drivers any "extra" volts is converted to heat. LD's I'm not that familiar with ..yet!
Now as far as the diode sheet specs.....it runs at 30ma, 2.15v. Lets give it 2.2v it's gonna need from the 9v battery and leaves 6.8v. (9v-2.2v).
Ok, plug 6.8v into the calculator and 0.030ma. You get 226ohms @ .204W.
So..a 220ohm resistor is pretty common and at 1/4W should work.
You can plug in diff values to simulate the voltage dropping and see what the current does. When it drops below the stated threshold current of 20ma, it should quit lasing.
Edit: I plugged it in and using the actual 2.15 as in Mario's example and a common 220ohm resistor you'll have 31ma.
You made a good decision in getting some cheap diodes to practice on. And yes, resistors are added up when connected in series. The trick for connecting them in parallel is to invert the resistance to get conductivity, add that, and then re-invert the result back to resistance. A 4, 8, and 12 ohm resistor in parallel would be calculated such: 1/(1/4 + 1/8 + 1/12) = (1/0.458) = 2.18 Ohm
The internet introduces an international community. English isn't everyones 1st language.
Many things on forums can be seen as "not how we do/say it", but the intent/content is normally easily understood. When I post anything that has measurements, I always include the mm equivalent as a courtesy. 99% of the world uses the metric system, we normally don't.
Toaster, have you measured the output of the driver where it connects to the dummy load? Just to see if the voltage is making it that far? From there you should be able to measure just after each diode and see a .7v drop. That would prove the driver is outputting and confirm each diode is working and installed correctly.
No output at the driver would mean its bad, or the connections are wrong someplace.