Drenthe, sometimes written as Drente, is a province in the Netherlands.
It is easiest to come by train from Utrecht, or Groningen (city). If you want to visit Emmen you can take a bus from Groningen (city) or take a train from Zwolle. By aircraft you can get in via Groningen Airport Eelde (IATA: GRQ), which connects the northern Netherlands with (among others) Milan Bergamo and Aberdeen.
Within the state, travel by bus is possible. But the best way to explore is by bike. As there are many little nice villages and small places to visit, it is a good idea to go exploring by bike. Many bikeroads have been build.
Rent a bike and explore. Visit little villages, have a drink. Take in some food in some of the excellent restaurants you will come across. If you are getting too tired, put your bike on the train.