Hope this helps!

Nether Portal Blocks:

1. Make a Nether Portal using Obsidian and Flint and Steel

2. Once the portal is made, face the purple swirly portal blocks.

3. Then use the pick block key (Middle mouse button)



End Portal Blocks:

1. Using an Eye of Ender, find the End Portal.

2. Using more of the Eye of Enders, fill up all spaces on the portal

3. Face the black portal blocks, and use the pick block key!



Spawners:

1. Find a Dungeon.

2. Face the spawner

3. Use the pick block key.



Pick Block Key Trivia

Using the pick block key on leaves will give the sapling from that specific tree.

Using it on Giant Mushrooms will give you the type of mushroom it originated from.

Usng it on Melons will give you a Melon Slice.

Using it on Glowstone will give you Glowstone Dust.

Using it on the End Portal Frame will give you the frame.

Nothing happens when you use it on the exploding crystals on top of the obsidian pillars in The End.

Using it on Bookshelves will give you a book.

You will get the specific spawn egg if you use it on mobs.