If you're using Raspberry Pi OS, the Raspberry Pi can be connected to Wi-Fi by adjusting the network settings in the taskbar.
Click the wireless icon.
Choose a network.
Enter the Wi-Fi password.
If you don't have a monitor, you can set the Wi-Fi information manually. This involves connecting the SD card to a separate computer and modifying some files. You can read more about how to set up a headless Raspberry Pi here.