I only know how to walk using eikin kor kor's map; check here, if you are good at reading maps and following road names which isn't that hard in Singapore just print the map and bring there and follow.
I can describe how to go, basically you exit Punggol MRT, go to the left side of the bus interchange, at this point your back should be facing the Punggol MRT station.. Walk along the left side of the main road (you should have to cross to do this), until you see a construction site on your left, when you see a big expense of field with a school in the distance at a traffic junction, TURN LEFT. After that just walk straight, you will see LRT track and a station on your right. Walk on, at this point the road will do a little curving left first, then right, IIRC, follow it, then straight on all the way, do not turn. Punggol Jetty and Punggol Beach is at the end.
Let me know if you have any trouble, hehe. If you drive or go by motorcycle, same way. There is a bus 82 that goes there as well, so if you don't feel like walking (~30-40 minutes walk depending on your speed), should be able to catch it at one of the bus stops you pass by on foot using the path I described.