Nashville tuning is a little more involved than just tuning your guitar differently. It's also known as high-stringing a guitar because different strings need to be used. It creates a 12 string effect on a 6 string guitar. The simplest way to explain it is, you use the high octave strings of a 12 string set of strings on a six-string guitar. The first two strings of your instrument (high E and B) remain unchanged, and the lower four strings (G through low E) are tuned an octave above standard tuning. It is possible to buy ready-made string sets for Nashville tuning but they may be hard to find. You can use a 12-string set ( just use the octave or thin strings) but that's kind of expensive. The best way for you may be to buy the strings individually from your local music store's single-string bin.
The gauges for a medium set would be .012, .016, .010, .014, .020, .030 high to low.
A light set would be .010, .014, .009, .012, .018, .027 high to low.
All strings are unwound except for the low E which is wound.
To tune them, use my 12 String Guitar Tuner and tune the strings to the High E, High B, and Octave Higher strings. You can use an electronic tuner and tune it just like you would a regular strung guitar the only difference is that the last four strings will be an octave higher than a normal 6 string.