To connect to Wi-Fi, click the settings area in the bottom right corner of the screen. Click Not connected, select the network name, enter the password, and then click Connect.
Although an internet connection is necessary to get the most out of your Chromebook, there are some options for working offline when Wi-Fi is unavailable. For example, you could work on an assignment in Google Docs or Slides offline, and then sync the updated file (or, in other words, save changes to the cloud) when a connection is available.
Not everyone has access to a home internet connection, but there are ways to get creative to get online. Many public libraries offer free Wi-Fi, along with some restaurants, retail stores, and coffee shops. If you have access to a smartphone that supports tethering and your plan has enough mobile data, you might be able to create a mobile hotspot to connect your Chromebook to the internet. Search for mobile hotspot setup instructions based on your phone service provider and hardware.