The first thing you see when you go to the nether is that there is lots of lava, fire, and Netherrack. Look up and you see glowstone, the brightest block in the game. When you break the glowstone, you get Glowstone Dust, which can be made into a block by putting 4 of them in a square on a crafting grid. You will also notice there are white creatures that look like jellyfish in the sky, called Ghasts. They can see you from 100 blocks away, and shoot fireballs that explode. However the explosion is not as bad as a creeper of TNT explosion, as it cannot break anything the same or more blastproof than cobblestone. There are also zombie pigmen, who hold golden swords. If you punch one of them, they all attack you. There are also Magma cubes, which behave like slimes, and drop Magma Cream.

I hope this helped,

Goodbye.