Wifi driver

It would help if you had posted the exact model number of your system. In general though go to the support page for your system and the driver should be listed under the specific downloads.

If your computer has an Ethernet port, connect the computer to your router. Once the computer sees an internet connection, use the Dell Update app and check for updates. The program should detect the missing WiFi drivers and will give you the option to download and install them. Alternatively you can use SupportAssist to update and install missing drivers as well. If for some reason Dell Update or SupportAssist doesn't find your WiFi drivers, you can try running Windows Update, which may automatically find and install the correct drivers.