I think he's asking about the config register...
router>en
router#conf t
router(config)#config-register 2102
router(config)#end
router#wr
Before you do this, try...
router>en
router#sh ver
It will tell you what the configuration register is set to. If it is set to 0X2142, then it will load the default configuration. Setting it to 2102 ensures that the configuration you have saved will be the one loaded when the router reboots. After configuring the router for everything, do thje "copy run start" or "wr" command at the privileged exec prompt (#).
Burt