The strings are numbered from thinnest (or furthest right as you face the guitar) to thickest (or furthers left) 1 - 2 - 3 - 4 - 5 - 6, 1 being the thinnest and 6 the thickest. This can sometimes be a little confusing because as you look at the guitar from the front, the strings are:

|  |  |  |  |  |
|  |  |  |  |  |
6  5  4  3  2  1

Good strings are important for sound and playability. It is recommended that you have a set of light gauge strings installed on your guitar for now. Light strings are easier to push down and won't wear out your fingertips as fast.