Part 4: Hardmode
As you advance the game you will finish the first stage, Pre-Hardmode. Pre-Hardmode has let you practice on what is about to come, Hardmode.
To enter Hardmode you will need to kill the Wall of Flesh. The Wall of flesh is the strongest boss in Pre-Hardmode. it will normally take several tries to kill it. To summon the Wall of Flesh you will need to throw a Guide Voodoo Doll into the lava.
I recommend for protection, Molten Armor and for a weapon I recommend Nights Edge. Remember this tip, the wall can only be damaged at the eyes and mouth.