Hi im trying to repair a 1996 geo metro i put a ignition switch in it now the geer want move when i press brake to put it in reverse or drive

Sounds like there is something faulty about the installation, as the ignition cylinder, the brake interlock and the shift lever are all interconnected. Or, it is possible the part used is not proper for the vehicle or is defective. You'll want to validate the proper application and quality of the part, and you'll want to recheck installation.