For example, when I go to Charms, there says I haven't started the course.
Can someone explain this?
You need items to start a course. Looking at charms on EU (I don't know what site you're on) I can see that you need the book "Charms and Curses", a White Quill, and a Wand.
Charms and Curses is a book and it can be bought at Flourish & Blotts along with the quill.
The Wand can be bought at Ollivanders.
You should be able to click on the items listed under "Requirements" and it would take you to another page :D
Customer support service by UserEcho