This page shows you how to add an email account to your iPhone; the procedure is the same for an iPad. I must assume that it is very similar on an Android device, but I don't have access to one to show you in detail.
Open your Settings, and swipe the screen up until you find Accounts and Passwords:
Touch it, and you'll see all your current accounts. If necessary, swipe the screen up until you see "Add Account"
Touch Add Account, and choose Google
You will see a Google login page. Enter your email address, and touch Next. Enter your password (page not shown) and touch next:
You will now have an option to pick the services you want to use, and the name that displays for this account in the Mail application.
I strongly suggest that you change the name of the account in the Description line - I use SCORE or Nuevas Sonrisas as my account names:
While you are here, there is one more setting that you might like to change. On the screen where you changed the Description, touch the Advanced button:
You will get to a screen where you can change some default settings to your liking. This is entirely optional, but I myself like to use the Deleted Mailbox when I delete emails - I am not interested in Archiving all my old junk like "OK, let's meet there" kind of emails. When I'm done with an email, I'm done. Here's what my Advanced Settings look like:
That's it. When you open your iPhone or iPad Mail application, the new account will show in your mailboxes:
If you are so inclined, you can change the order of your Mailboxes: Touch "Edit" at right top (shown in the screen shot above, and then you can grab an account by the stack of three horizontal lines on the right and move it up or down.