How do I print onto A5 size paper please?

Using LibreOffice 4.2 on Windows 7 home premium. My Printer is an Epsom Stylus Office BX305FW Plus
Want to know how I can print Libre documents onto A5 size paper. I know it can be done because I am sure I managed to do it some months ago but I have forgotten exactly how I managed it ?

Stuart Shaw.

Format > Page > Format > A5

Caesar whoever you are , THANK YOU. Your help is much appreciated.

Stu