How do I get to The Nether in Minecraft?
You will need to create an upright portal, consisting of an obsidian frame, leaving an 2x3 area free on the inside and use flint & steel to set the inside on fire.
After you have set the inside on fire, the inside will change in a purple swirly portal.
just for reference, Obsidian can be made from flooding water on top of lava and mining it with a diamond pickaxe. (or if you're truly hardcode, make the obsidian in place using lava and water buckets)
Before setting fire to it
(note that the complete bottom of the portal is also obsidian.)
After setting fire to it
I have heard that you don't actually need the corners -- 10 blocks of obsidian is enough.
Keep in mind you need to _stay_ in the portal. Simply going through it is not enough.
An important thing to remember is that making the obsidian in place doesn't require a diamond pick. Between not having to find diamonds and not having to mine the obsidian you can save a lot of time (if you have enough buckets).
@lunboks I added replacement images. The old images weren't hosted on Stackexchange, but the new ones are, so hopefully they shan't need to be replaced a second time.
Is it possible to make a 6x4 portal? I screwed up with my count, and since I don't have a diamond pickaxe, I can't destroy it. With my 6x4 portal, when I light the inside on fire, nothing happens. Will it be fixed if I add two more obsidian blocks to make it a 5x4 with a line of obsidian below?