Dear oh dear. Roll on holiday.
No-one can give you a 'recommended' resistor value unless they have the product Data Sheet.
At last you now give a supply voltage - that helps!!
What
YOU should be doing is searching through DATA SHEETS from places like Farnell for similar spec LEDs.
I don't understand how you have all the specs except Imax? Are these some cheap chod from Ebay?
Specs can vary, but a little one like that should be safe (fingers crossed) at
20mA. (Specific 'low current' LEDs are an exception). Many are fine at
30mA continuous.
But no-one can guarantee it. If it pops then tough and buy some with a Product Data Sheet (sorry, that's life).
And, if you are going to persue electronics, PLEASE learn how to use a multimeter. Ask your teacher/relatives/friends for help. This is a really basic piece of kit which is IMPORTANT.
FINALLY: we are assuming you will be running DC through this mystery LED. You can go higher when pulsing, but this varies with duty too. But lets leave that until you have a device with some proper Data...
For now, assume 20 to 30mA.
As for the R value ... you can do the calcs from your equation (?).
If not, Westaust will do it for you