Touching the top of the world requires you to build up to the top horizontal edge of the world (the opposite of Rock Bottom achievement). For beginning players, you will need to build up using blocks, rope, or platforms. This will make a pathway up to the top, but you can easily fall off or be knocked off by enemies. The best way to each the top is to create a Hellevator/Skyvator close to your home base, building an upper part reaching into the sky (Skyvator). You can use the materials you remove digging down to make the Hellevator to build the upper portion if you are early on the game, such as stone or dirt.MAKING A HELLEVATOR/SKYVATOR
1. A fast pickaxe is recommended since this will require a lot of digging.
2. Make a hole leading straight down, at least two blocks wide (I recommend five because you can add walls later and line it with material to keep enemies out).
3. Place platforms across at intervals to prevent falling damage, or bring some buckets of water and drop them at the bottom to make a little safe landing area.
4. Add some light sources.
5. You can make branches out to the sides (and add doors if you want) to access underground areas for mining ore or exploring.
6. A Hellevator prevents you from being hit by making a wall on either side of you. This allows you to go up and down without being hassled by enemies.
This is also useful for going for
The To Hell and Back achievement in Terraria worth 85 pointsTravel from the Surface to the Underworld and back in one fell swoop.QUICK SOLUTION
***Same as 360 version***