you can't.
http://www.bba-reman.com/content.aspx?content=Test_for_Renault_Key_Immobiliser_failures_emergency_recode
bought a second hand card key for laguna 2001 to reprogramme the key for my car what do i do
How do I re program my key fob for renault laguna estate 1997?
8 mm square key
KEFON
Insert your key in the ignition. Turn it to accessories. Press your remote lock button until you hear a beep. Now it's configured!
Weak battery Loose or corroded battery cables
If your Renault Laguna's key card is broken, you can lock the vehicle manually using the physical key, which is usually hidden inside the key card. To access it, slide the release button on the key card to extract the metal key. Use this key to lock the driver's side door. Alternatively, you can use the vehicle's central locking system from inside to secure all doors.
You can ask to a Renault dealer. They have acces to Renault database and can give you these code free of charges!
See the link for further info on how to fix
You can't, the equipment to do that is too expensive to buy. You'll need to take it to a dealer to have it done. most charge around $80.00 to recode a key !
With proof of ownership and the vehilce VIN you can obtain a duplicate key from a dealership. A dealership may have the software needed to recode a key if necessary, as keys are vehicle specific.