The Legend of Zelda: Majora's Mask Walkthrough

Majora's Mask p.4

DEKU NUTS
In this room, you'll have to use these flowers to go from one island to the other. Get in the first flower and fly to the second platform. From here, there are two platforms ahead. Fly to the one on your left and open the large chest to get your very first item: Deku Nuts. While you won't be fighting enemies for a little while yet, these are very useful things to have, allowing you to briefly stun foes and make them vulnerable to attacks.

To your right is a tree. The fourth platform is right behind it, so you can either try and fly around it, or go back to the second platform below and then go to the fourth platform. Once you make it, look off in the distance to see the fifth platform. Get in the flower and go around the tree, then straight for the platform. You should just be able to make it.

Tatl will inform you of the thingy over on the other side (attempting to teach you how to use either Z or L targeting). Check it out if you like, then fly over to the final platform. Press A to inspect the weird tree (looks like a Deku Scrub doesn't it?) and go through the last entrance.