Performing a system recovery is destructive process and will destroy your as-is system and data, and return it to as-shipped state.
Basically, to perform a system recovery from your recovery disk(s) [which is what I assume you mean by 'install recovery discs], insert the (first) disk in your CD or DVD tray, and turn your computer on; enter the BIOS set-up and select boot device = device in which you have put your recovery disk. Save the changes, and continue to boot. Subsequently, simply follow the instructions in the menu.
I recommend you follow your manufacturer's instructions for performing a system recovery. HP's are here http://h10025.www1.hp.com/ewfrf/wc/document?cc=uk&lc=en&dlc=en&docname=bph07145#N449
A more general outline is given here
Do not forget to update your drivers and other software after you have finished because what you have recovered to is the state that your computer was in when it left the factory, not the state it was in immediately before you performed the recovery. (barring any hardware changes that may have occurred of course)