I'm not sure if you need to be 'Full Access' or not, but if not, there is a guitar 'Reference Tuner' under the Tools drop down. I'm certain you can Google up something similar if you can't get at it.
I think almost anybody would recommend learning to tune by ear, although you could go out and buy a tuner as well. However you do it, you want to avoid way over-tune your guitar lest bad things happen.
I only started learning to play lead a couple months ago and this site has been a great help. Good luck!
...so ever since then, I always hang on to the buckle.