Enter Service Tag # here to get the exact driver under Network drivers: Drivers and Downloads | Dell [United States]
Otherwise if it doesn't say in Device Manager which model Wireless device you have, then you'll have to try each of the wireless drivers.
You can also trace it using Hardware Identification
to find out which make/model Wireless device you have.
What is listed in Device Manager under Network Drivers, or which drivers in the main list have an (!) exclamation mark indicating they need drivers.
All of this was spelled out in detail in the tutorial you didn't read.