I thought you only need to include the new header name (<%include myheader.html%> in the "Header" field and the new header template (myheader.html) will automatically show up in the targetted template.... !!!!
Means if I created a new header template (myheader.html) using Build>User Templates ... then I went to Browse>category>Edit and put <%include myheader.html%> , then myheader.html file will show up automatically in the targetted template without even including the <%Header%> tag in the targgetted template category.html ... am I wrong or wrong!!!

Then how come I read other threads that say:
".. u just need to type the name of your new header template in the Header field..."
very confusing... am I missing something here...

thanks again..