How can I secure my WiFi with a pass code?

if you plug you modem directly into your computer, then open your browser and goto 192.168.1.1 (this is typically the default ip address to access your modem settings). It’ll ask for U/N and P/W which was admin / 1234. This has worked for 3 different modem manufacturers for me. If that works look for security settings then WEP (that’s the encryption). If you have trouble getting into your modem’s settings, you should just call your service provider.

It would be helpful to know what kind of hardware you’re using. It sounds like the wireless network hardware (probably has antennae sticking out of it) was reset. What is the make and model of that?

The best way is:
Google>[model] user manual .pdf

@gsiener. The hardware was indeed, reset. It’s an Edimax BR-6216Mg.

Looks like you can find the manual here.

Go to page 43 and follow the steps to enable security. I would recommend WPA over WEP, and make sure you pick a strong password (not a word you can find in the dictionary).

Hint: this will be easier if you’re plugged in via ethernet cord while setting up.

The most secure way to secure your wi-fi would be to just avoid WEP encryption completely; I’d use a combination of WPA2-PSK security and a MAC address filter, both of which can be set up via the router configuration page (usually http://192.168.1.1 or something similar).