This article will show both the basic storyline and a walkthrough of the chapter. If you did this correctly, you should be trapped in the Nether with absolutely nothing at all to defend yourself with. Prepare yourself, and be ready to die. A lot.
There are a few major decisions in this chapter that will decide whether you actually return to the Overworld, go to the next chapter, or die Hardcore mode-style. The first thing you should do is to get a wooden sword... Wait, there's no trees in the Nether, so we'll have to do with what we have... which is absolutely nothing. Oh, wait, there's some Soulsand over there, let's use that. Go ahead and build a Soul Crafter like you would a Crafting Table. But with the Soulsand we just got. The Soul Crafter behaves almost exactly the same as the Crafting Table, except you can't cook with it. What's next? Craft Hellish Staffs by using two Soul Sand on top of each other, like you would with Sticks. As awesome as the name sounds, it's just a stick, just made in hell. Craft a Soul Sword like an ordinary sword, just exchange the wood planks with Soulsand and the sticks with Hellish Staffs.
Voila! You now have an anti-Ghast weapon. Just don't punch a pigman.