Install Centos 6.7. Version 6.2 is not maintained anymore.
Then a few questions.
Did you sign in to your Google account before accessing gmail.com?
What do you see when you try to access gmail.com?
Can you access google.com?
Can you access accounts.google.com?
Can you sign in?
Can you access support.google.com and follow the suggested troubleshooting steps for Gmail? In particular
https://support.google.com/mail/trou..._topic=3406259 ("gmail is slow, unresponsive or not loading").