How to Get Dark Souls Dragon Greatsword?

I've just found an useful Dark Souls walkthrough video from Youtube! So, I want to share it in here. In this Dark Souls walkthrough, you can learn how to get Dark Souls Dragon Greatsword. Dragon Convenant is located in Ash Lake and you can get Dark Souls Dragon Greatsword from the tail. You're also can get the Dragon Eye and Dragon Head Stone if you join the convenant. For complete walkthrough,