From The Document Foundation Wiki
- create a new Writer file which will be the source file for the headers;
- enter the text that will appear in the header of the body of the file;
- save the file as a Writer text;
- create a new Writer template which will serve to build all the other files that will have the same header;
- select ▸ ▸ ;
- with the cursor in the header, select the ▸ menu;
- check the Link box and click the Browse... button to select the source file;
- press Insert; and
- save the file as a template:
- select the ▸ ▸ menu;
- give a name to the template; and
- press OK.