Path analysis D-FLIP-FLOP - what is SET?
The only part of the datasheet you will need to look at for this is the truth table. 



The sentence in your question does not appear in the datasheet you linked, so I could be wrong with your interpretation (assuming that this was the task given to you). 

The outputs of the Flip Flop are Q and inverse Q (the one with the line above it). It is (obviously) the inverse of the Q output, so if Q = 1, then inverse Q = 0.

Now look at the left hand section of the truth table. You can see the column with Preset and Clear. The 'H' and 'L' are to indicate high and low (1,0). The CLK is your clock. The up arrow indicates when the positive edge is triggered, and the 'X' is a 'don't care' state. The 'D' is the data in.

All you need to do is match these up to get the outputs you require. So, if you want the Q output as a 1 and inverse Q as a 0 on a high clock pule, consult the truth table. You can see that Preset will need to be High, Clear needs to be High and the data needs to be High.

This table will let you figure out any configuration of the input pins to get the desired output.