...
Define a fragment for the default user (e.g. fragmentTemplate) (see example in the file). Inside this fragment, you should include the header and footer folders. These will be propagated to all the rest of the fragment users in the file that have the includeDefault="Y" attribute set.
Syntax is pretty much the same as for fragments.xml (but with a dlm: namespace). One extra attribute was added to the "folder" tag, "width", which lets you specify the width of a column.
...