After you successful registered in gmail, you are now possible to look at the interface from your new mail provider. Please click on the link "postbox" to go to your received mails.
On the next page, you'll find lots of useful links.
At the top, you have listed all google services (news, mail, groups, Youtube etc.). In the middle, there are features like write an e-mail, edit your labels, your folders (postbox, bin, spam, sended mails).
To all these points you can easy and quick navigate in the link list. To show you all links on the website, press NVDA+F7. For example if you want to go to your postbox, please press the letter "p" in the link list until the screen reader says "postbox."
I hope, these instructions aren't wrong. Here in Germany, I can only use gmail in German language so I can only describe the leyout how it looks in German, but I think it should be the same too in english. May be the names of the links are different, but if you look at the website, I'm sure you will manage it! An now, have fun with gmail!