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
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.