Do you have a gmail account? If not then use your regular PC to create an account first.
Then you should be able to sign in with your tablet.
Just a thought, do you have the G-Mail App installed?
Mine works perfectly.
I can set up one gmail acct through the email on the tablet. But I can't download the gmail app as it says my device is not compatible. I would really like the app. I have gmail handling email from a different email account that I can't setup through the tablet's email. Example: Username/email: firstname.lastname@example.org. To set up on the Tablet's email I would have to enter it as: Joeshmo@email@example.com which of course it won't. The Gmail app allows me access that account.