Summarize the following:
One of the best things about Google Calendar is that you can use it on nearly any device. If you're using a computer, visit https://calendar.google.com in any web browser. On a phone or tablet, tap the blue-and-white calendar icon labeled "Google Calendar" (iPhone/iPad) or just "Calendar" (Android).  If Google Calendar isn't on your Android, download it from the Play Store. If you're using an iPhone or iPad, you can download Google Calendar from the App Store. If you're already signed in, your calendar will appear. Otherwise, you'll be prompted to sign in now.  If you use Google Calendar on the web or elsewhere, signing in with the same Google account now will automatically sync any existing calendar events.  Visit https://accounts.google.com/signup to create a Google account if you don't already have one. To open your settings, click the gear icon at the top-right corner (on a computer) or tap the three-line menu at the top-left corner (phone or tablet), and then select Settings.  Tap General on your phone or tablet to change the starting day of the week, time zone, default event settings, and more. If you're using a computer, Settings opens to the General tab, on which you can adjust your language, time zone, default event settings, and starting day of the week. Use the menu on the left to see additional settings. When using Google Calendar on a computer, you can customize some color and size options by selecting Density and color from the Settings menu. Your calendar will open to the current day, week, or month, depending on your settings. Here's how you can switch the view as needed:  Mobile: Tap the three-line menu at the top-left corner, then select Day, 3 Day, Week, Month, or a different option to switch the view. Computer: Click the drop-down menu at the top-right corner (it should say Month by default) and select Day, Week, 7 days, or a different option. In addition to viewing your own calendar events, you can see someone else's events and agenda by subscribing to their calendar. If the calendar you want to follow is public or has been shared with your Google account, follow these steps to subscribe: Go to https://calendar.google.com in a web browser (this feature is not available in the mobile app). Scroll down the left column and click + next to "Other calendars." Click Subscribe to calendar if you want to add the person by email address or by selecting them from your contact list. If you've been provided a shared calendar URL, select From URL instead. Find and select a Google contact or enter the shared calendar's URL. Click Request access when prompted if you're not already approved to add the calendar. Once the calendar is approved, it will appear in your calendar list anywhere you log into Google Calendar. Google Calendar lets you manage multiple calendars within a single account, which is great for managing work appointments, personal events, holidays, and additional tasks.  Click or tap the three-line menu at the top-left corner to expand the menu. If you're using a computer, you only have to do this if you don't already see a list of calendars in the left panel. Use the checkboxes next to each calendar name to make a calendar visible. If you're just getting started you'll only see a few options, including Availability, Reminders, and sometimes some holiday options.

Summary:
Open Google Calendar. Log in with your Google account. Customize your calendar's look and feel. Choose which dates to see. Subscribe to another Google Calendar. Control which calendars display by default.