How do I insert page numbers and format the numbering of the numbering?
Insert → Field → Page number. You can change the page number format by modifying the page style in use. Check LibO’s help for more information on Fields and Page Styles [you can also check this free book about Writer 
] If you still have problems, please, provide more details on what you need.
Note: please, don’t use the “community wiki” option for questions or answers!