Before coming along to your first lesson you might want to get started. Here are a few materials which will be useful.
There are a few different ways to tune your guitar. The easiest is to use an app and I'd suggest
Here is a sheet on a few different methods too. gallery/tuning the guitar pdf.pdf
Your first song will be Greensleeves. If you watch the video below, I am playing the melody while Arran is playing the open strings which you will try. Keep your part like a clock ticking along. Here is your music gallery/the strings and greensleeves pdf.pdf
Your next move is to use the pick and fingers of the fretting hand. For this watch the video below and use this music. gallery/james bond.pdf . You will also need to start reading tab. This will give you a starter. http://www.wikihow.com/Read-Guitar-Tabs
I have written my own tutor book and this is used within the my classes and individual lessons where appropriate. It includes videos on YouTube which accompany each song. Search The Rounded Guitarist on YouTube for videos. I also use various other materials including Trinity Pop and Rock, Rock School for pop and rock and Associated Board of the Royal Schools of Music for classical.