You will need; a TV or computer monitor connected to a Raspberry Pi connected to your network. A computer with LibreOffice installed on it. And something with a 'web' folder on the same network (such as a NAS box or computer with Apache Server running)
Lets say the the web folder has the adress \\192.168.0.2\web\
On the computer with LibreOffice open sweb.exe (to do this on windows run C:\Program Files\LibreOffice[version number]\program\sweb.exe) then compose the page you want to be displayed:
and save it into \\192.168.0.2\web\ as, for example whiteboard.html
Then open the file with notepad (or similar) and add the line highlighted below:
and save he file.
On the Raspberry Pi, in Midori (web browser) open http://192.168.0.2/whiteboard.html
Then alter the view to fullscreen.
To change whats on the screen; edit whiteboard.html using sweb.exe save it and the screen will update in less than 60 seconds.