1. http://www.minecraftforum.net/topic/600254-surv-skyblock/ < Go there
2. Scroll down until you see "Download Skyblock 2.1" if you want to do the hardcore one, then click that one, I wouldn't recomend it though, cause' if you die, you have to restart. xD
3. Then click "Skip add" in the top right corner.
4. Click the one that says " DOWNLOAD 2.0 MB) " Then click save. Name it whatever you want. xD
5. Go to you documents, and click download, then click the file you saved skyblock on, then leave that tab open.
6. Click the thing at the bottom left corner of you screen, then type in the bar : %appdata% Then click enter.
7. Find the bar that says : .minecraft Click it.
8. Go to your saves file in the .minecraft bar.
9. Go back to your Skyblock download, and right click it, find the thing that says : Open with. Click winRAR achiever
10. Drag the one that says : SkyBlock2.1. Into your .minecraft save folder. Make sure you don't drag it into a different save! D:
11. Go onto MineCraft, and go to singleplayer, and start playing. :) It should make a new save that says : SkyBlock.
12. Have fun. :D