THE FULL WALKTHROUGH IS AT http://poptropicarticles.blogspot.com/2013/10/virus-hunter-island-walkthrough.html
Note: I wrote this walkthrough myself. Because this is the new version of Poptropica, there are still some bugs and it may not save. You can NOT customize. For now, I recommend a casual outfit like the one in http://poptropicarticles.blogspot.com/2012/11/special-effects-on-poptropica.html.
Visualize this map:
apartments - Globalchem (Main Street) - Video Store, Fitness place, Falafels
1. Go right and enter the fitness place. Go left and click on the rubber-brand colored thingies. The person kicks you out, and you get to keep the rubber bands.
2. Go left to Globalchem and climb up the tree on the right side. Jump onto the bus bench, then the tree. From the nest, "use" the rubber band to latch onto the hook. Climb up and talk to the guy on the roof.
3. Go left. Jump over the wall and talk to the pizza guy. When he drives off, pick up the shredded papers.
4. Go back to the guy on the roof. You need to put together the blue and tan pieces of paper. He gives you a fake PDC badge.
5. Go right to the video store. Enter and you show the guy your badge. Go down the elevator and talk to Dr. Lange. Watch the video, then she gives you a camera and dosier.
6. Exit and go left to the apartments. Click on the recycling bin and find the letter and postcard to "Joe Stockman".
7. Go right to the falafel stand. Talk to the guy with the apron, then follow him into Globalchem. Go up and back-and-forth until you get to the guy on the very left top - Joe Stockman. Talk to him and "use" the camera.
8. Go back to the video store and show the picture to Dr. Lange. Next, follow her into the room that will basically shrink you.
END OF DEMO!