.docx files cannot be opened on github , download them  and then open . 

learning path :
Download java-full-stack-pratice-programs repository
Once downloaded open the "Full_stack_java_pratice" folder with any IDE
 ( intellij idea recommended    https://www.jetbrains.com/idea/download/?section=windows  install community edition) 
 
 "Java_Documentation"  folder consists of word files open it with any doc reader  ( word  (or) google files ) .
 
 go through the concepts in documentation folder  in  the same order . 
 For every concept  check the corresponding examples code in IDE .