to get an ender pearl, you need to deal with an enderman and pick the pearl up after the enderman has been slain. once in possession of the pearl, take 2 stacks of 64 of any block (i used dirt) and place them under you by jumping and placing a block. once on top of the 2 stack pillar (128 blocks high) simply throw the pearl using left trigger. do not worry if the pearl looks like it disappears it takes a while to drop all the way down. the achievement unlocks once you spawn on the ground.
*edit* according to mama berry, you can trade with one of the purple robed 'cleric' villagers in the village, near the starting spawn in the Elytra tutorial world, a couple of times. There's enough emerald blocks lying around to have more than enough emeralds! After a couple trades they should hopefully offer Ender Pearls, likely between 5-7 emeralds a piece. Hope that helps!
*edit2*gobey17 pointed out that the cleric villager spawns in the village to the left in the elytra world (at X: -97, Y: 86, Z: -37)
You do however need a handful of gold ingots to start off with to give to the cleric in exchange for a emerald (meaning having to mine a gold block with a iron pickaxe to make some, which one block can be found where the Elytra wings are on a small pillar). Then just gotta give a few more emeralds to get the ender pearl. Thanks for the tip Mama Berry!
so there are 2 ways to do this from what i see.
1. kill an enderman and get the pearl. stack up 2 blocks and throw the pearl forwards (at the horizon ((horizon goes left to right))). done
2.take the blocks or iron from the chest at X:-30, Y: 80, -79. there is wood right next to it and a crafting table. make yourself some iron pickaxes.
at X: -23, Y: 86, Z: -121, there is a gold block. across from it, at X: -9, Y: 86, Z: -119, are 2 blocks of emeralds. take those down as well. using the gold and the emerald, trade with the purple robbed cleric villager at X: -97, Y: 86, Z: -37 to obtain the ender pearl. make an iron shovel and dig in the hillside for dirt, or use the iron pickaxe for cobblestone. get 2 stacks go all the way up and throw the pearl at the horizon.