PLEASE STOP LEARNING TO USE WEBDRIVER/SELENIUM WITH GMAIL AS THE APPLICATION UNDER TEST. [ I intentionally used all caps to emphasise what I was trying to say ]
GMail is extremely complex Web application and you would be wasting your time trying to sort things out with its extremely dynamic UI, than learn anything on Selenium/WebDriver.
The only valid scenario wherein you would need to automate against GMail is if you are working for Google and on the GMail dev/qa team.
Please pick a site that is relatively simple and start from there.
I remember there were a couple of posts by folks in this forum with respect to some test sites that you can use for learning automation. Perhaps you could search the forum and start off with those sites.