Instructions to install a custom map : Here

Call of Duty 5 - World at War

Copy the (custom_map) folder with it's contents to:
(Win 10 , Win 7)
**Important : Must have hidden files & folder OFF**
Where to find USERMAPS folders:
DRIVE_LETTER:\Users\YOUR_USERNAME\AppData\Local\Activision\CoDWaW\usermaps