Getting your printer connected to Wi-Fi is one of those tasks that should be easy but sometimes isn't. The process varies a little depending on your model, but the general steps are the same across most printers.
Start by making sure your printer and your computer or phone are on the same Wi-Fi network. This is the number one reason wireless setup fails. The printer connects to one network and your device is on another. Check both before you do anything else.
On most LaserJets with a touchscreen, go to the network settings menu and select Wireless Setup Wizard. The printer will scan for available networks, pick yours, and enter the password. Use the touchscreen keyboard carefully because it's easy to mistype characters, especially passwords with special characters.
For models without a touchscreen, you'll use Wi-Fi Direct or the printer's mobile app to connect. Download the app on your phone, follow the prompts, and it'll walk you through the process. It usually takes about 5 minutes from start to finish.
If the printer connects but you can't print from your computer, the driver might not be installed. Go to the manufacturer's support site, download the driver for your specific model and operating system, and install it. During installation, choose the wireless connection option. The installer should find the printer automatically if it's on the same network.
Still having trouble? Restart everything. Router, printer, computer. In that order. Sounds old-school, but it fixes connection issues more often than you'd guess.