There are several ways of moving between towns in Belarus.
Certainly, if you arrived in Belarus in your own car this problem is solved for you. All you need then is a road map that you can buy at a bookstore.
For those visitors that did not bring their vehicle with them there is an option to rent one. There are offices of Avis and Europcar in Belarus as well as some other local renting companies.
As regards public transportation there are the following options: bus, train and air.
There are very few local flights in Belarus and they are not very frequent. That means that you can only get to some oblast centers once or twice a week.
More useful are bus and train.
Tickets and timetables are available at respective train and bus terminals.