Gmail and Google Calendar apps for Android
Our recommended solution is to download and use the Gmail and Google Calendar apps from the Google Play Store. These apps are free and offer more integration with Gmail than the built-in apps. Since your Android is a Google device, chances are you already have these apps.
Gmail app: https://play.google.com/store/apps/details?id=com.google.android.gm&hl=en
Google Calendar app: https://play.google.com/store/apps/details?id=com.google.android.calendar&hl=en
Step By Step Instructions (Gmail and Google Calendar apps)
Launch one of your Google apps. Setup is the same for both of them.
Add an account
Open the Gmail or Google Calendar app.
On the top left, touch the Menu icon 
At the top of the menu screen, go to the right of your username and touch the down arrow.
Touch Add account.
Choose the type of account you want to add: Google: A Gmail or Google for Work address.
At the sign-in page, enter your email address at swarthmore.edu.
On the next page, enter your Swarthmore username and password.
Switch between accounts
If you have more than one Gmail account, messages on the Gmail app stay separate for each account. To switch between accounts: