The very first step that you should take is to check if your printer is powered and the Wi-Fi is working.
Take a piece of paper, or open a note app on your phone and write your network’s security password and SSID. If you don’t know what an SSID is, find out here.
On the printer’s control panel, go to Settings, and then, Network Settings.
In the Network Settings menu, search for Wireless Network, and press on that. Now your Brother printer will search for the Wireless networks in your proximity. Look for your network and press on that.
Now that you have selected your preferred network, enter the password for that network. Once you do that, the printer will connect to your Mac.