Header.md

-This page describes the content of a CZML document. Please read [How to get started]() for an explanation of how a CZML document is put together.
+This page describes the content of a CZML document. Please read [How to get started](How to get started) for an explanation of how a CZML document is put together.
 
 # HEADER
 
@@ -31,20 +31,20 @@ The header is the first object of a CZML file, it describes for example what kin
 
 **name** - String : Name of the header, describes what have been used to build it
 
-**Clock** - [Clock]() : The clock object, describes when the study will be done.
+**Clock** - [Clock](Clock) : The clock object, describes when the study will be done.
 
 
 # Build
 
 A header can be build with  :
 
-* An Id, a name, and a [Clock]() :
+* An Id, a name, and a [Clock](Clock) :
 
 ```Java
 Header header = new Header(id, name, clock);
 ```
 
-* An id, a name, a version and a [Clock]() :
+* An id, a name, a version and a [Clock](Clock) :
 
 ```Java
 Header header = new Header(id, name, version, clock);