Many of HeadWize library contains require some knowledge of electronics. However, Many does not.
Some can instruct you to understand audio electronics so that you can understand higher and more complex designs.
Unfortunately, the very basic understandings must studied. But do not be frightened. High school science textbooks with a chapter on electricity does excellent job. I recommend you read a bit on opamps. Then you read Mr. Moy's article on opamps. Then you should be able to understand most of the materials in the HeadWize Library.
You should probably not do tube designs. You can electricute yourself. Leave them till you are seasoned.