I think the reason people are telling you to be cautious is, if you are unable to distinguish the anode and cathode from that datasheet/schematic, then there is a high risk of you damaging the laser diode (they are very delicate, and easily killed with static, over voltage, over current, over temperature.. harsh language etc..) and it also shows a lack of understanding and as such, possibly unaware of the real dangers to your eyes.
Please dont' take offense to this, I am not trying to put you off. Just that you should be aware of the requirements of driving laser diodes - it isn't just a case of a "constant current supply", you'll need circuit protection. And to stop you wasting your money by destroying a laser diode (I've destroyed about 3 whilst testing a circuit before) to read up, and test on red LED's first. LED's are similar - they are diodes and as such exhibit much of the same characteristics but do not cost as much, and cannot blind (assuming you're dealing with 5mm ones).
In regard to your question, the schematic shows the laser diode and photodiode in three configurations labelled A, B and C. It clearly states the pin numbers of the laser diodes anode and cathode with "LD" - laser diode, and "PD" = photodiode - used for feedback for the driver to achieve a relatively constant optical output power (laser diodes optical output depends on temperature, and so varies greatly during operation).
You ask about ground, that is a relative term, but I'm pretty sure you mean cathode, or negative terminal. Many constant current drivers use low-side current sensing, so the negative terminal of the laser diode isn't actually at "ground" potential, best to use the terms "anode" and "cathode".
edit: apologies to other posters for effectively echoing what they said. Wasn't sure if the OP understood or just skipped over the replies so I thought I'd reiterate.