Insert the leads of the IS471 into the perfboard close to an edge. The leads will need to be spread out just a bit, since they are spaced more narrowly than the average perfboard holes/pads. Note that the flat side of the IS471 needs to face outward, since this is the side that "sees".
Bend the IR LED to the right as shown below. With the LED positioned as shown the short lead (the cathode) is on top.