I published a ROBLOX book called ROBLOX Building Guide. It teaches the basics of ROBLOX Studio, the program for creating ROBLOX games. There are also intermediate tips if you already know ROBLOX Studio well. It is in form of both eBook and print!

http://www.amazon.com/ROBLOX-Building-Guide-ebook/dp/B00EDZDAAK/ref=sr_1_2?ie=UTF8&qid=1375994341&sr=8-2&keywords=roblox+building

I also have another website in which I will post all my newer ROBLOX-related articles, news, game reviews, and more:

http://www.robloxbuildingguide.com/

In terms of difficulty, ROBLOX Building Guide is meant for beginners, but it gives a lot of insightful tips for anyone who wants to create a ROBLOX game, with tips to get around tricky situations in ROBLOX Studio, creating games, and more!