Before reading this, I'm sorry if this is terrible, I've never made a guide. I thought this MIGHT help someone with the download.
First, go to the Episode 300 Video. Look in the description for the "Episode 300" link, and download it. WARNING This is a very large file, and download with this knowledge.
Second, drag and drop the saved file into your .minecraft saves folder. To do this, search your computer for "run" and open it, in the space type in %appdata% once there choose .minecraft and then the "saves" folder.
Third, make sure you have file opening software, such as 7-zip. I reccomend 7-zip due to it being ad-free and easy to use. If you do not, google "7-zip" and download it.
Fourth, open 7-Zip File Manager and locate your ".minecraft\saves" Find the "Episode 300" file, it should look like a white page, open it with 7-zip.
Fifth, open 7-zip again, locate your .minecraft\saves again and make a new folder named "Episode 300."
Lastly, Drag and drop all the files from the Episode 300 file into the Episode 300 folder.
You should now be able to play on Scottland by opening your minecraft and playing "singleplayer."