Tunisia is generally known for its beach holidays or ancient ruins at Carthage or El Jem. The former I’ve experienced, the latter unfortunately not.
Getting around the country by train is simple enough, timetables for which are sometimes available on the Tunisian Railways (SNCFT) website, however if they’re not then they are available on the Fahrplancenter website, which also lists timetables for many other places throughout the world.
For the tourist wanting to travel a few times during their stay it is well worth considering buying a Carte Bleue. This allows unlimited travel throughout Tunisia for a set fee in three different classes. The only fare then payable is an admission to each train (long distance trains only not local trains) which even in comfort class is a very minimal cost.