Current version of Libre Office: 4.4.4.3
Operating system: Windows 8.1, language: Dutch
Hopefully, this is what you want.
Click on the following: “Format”, then “page…”, then “Page Style Default”, next click on the “header” tab, then finally click on the “edit” button. From here you will be able to set your “headers” for all pages. This based on version 5.2.5.1
If your “headers” are rows to repeat, then you need to define print range and edit it (using Format->Print Ranges->Edit...) to define repeating rows (and columns, if required) there.