You can add your account to the Gmail app on your smartphone or tablet or sign in from a computer to access Gmail. Open your inbox to check your mail once you’ve signed in.

On Computer

1. Go to gmail.com on your computer
2. Enter your password and email address for your Google Account.
   • Click Use another account if the information is already filled in but you need to check in to a different account.
   • Click Sign in in the top right corner of the page if you see a page describing Gmail rather than the sign-in page.

SIGN IN TO GMAIL

Tip: Make sure to sign off of a public computer after signing in if you’re using one. Find out more about securely signing in

On Android

On your Android phone or tablet, you can add both Gmail and non-Gmail accounts to the Gmail app.

1. Open Gmail On your Android phone or tablet.
2. Tap your profile picture in the top right.
3. Tap Add another account.
4. Choose the type of account you want to add.
5. Add your account by following the steps on the screen

On iPhone or iPad

On your iPhone or iPad, you can add both Gmail and non-Gmail accounts to the Gmail app.

1. Open the Gmail app on your iPhone or iPad .
2. Tap your profile picture in the top right 
3. Tap Add another account.
4. Choose the type of account you want to add:
   • You may need to enter specific settings or an app password if you use iCloud, @me.com, or @mac.com accounts
   • Select Outlook, Hotmail, and Live if you check work or school emails through Outlook for Windows
   • Select Other if you don’t see your email service
5. Follow the steps on the screen to add your account. If available, tap Try Gmailify to get Gmail features with your added account, like spam protection and email categories.

Source: https://support.google.com/mail/answer/8494