One way ticket from Tokyo to Kyoto

Hi,
You can buy your ticket in any JR train station.
You can see regular fares, routes and schedules on Hyperdia.
The fastest train is the Nozomi bullet train and you can arrive within 2½ hours. Unfortunately, if you are only taking this trip, a rail pass would not pay off for you. The cheapest ticket would be for an unreserved seat, and cost about 13,080 yen. There are trains leaving every 10 minutes or so.
Since no rail pass would work for you, if you wanted to save a little money there is the Platt Kodama Ticket and you'd save almost 3000 yen - but there is no such thing as a free lunch. The Kodama bullet train stops at every single bullet train station, so it would take you an extra hour to get to Kyoto. You'd also need to buy the ticket at least a day in advance. So it's up to you.
You should definitely not miss Nara either for your travels - it has some of Japan's best sights.

Good luck.

Thank you for your time and useful advice.
Greetings,
Vanja