Gare de Wissembourg (Wissembourg train station) receives local trains from Strassbourg, France and Neustadt an der Weinstrasse, Germany. The trains from Germany arrive and depart roughly every hour, while the trains to Strassbourg are more sporadic.
If you are coming from Germany, be aware that all trains arriving in Wissembourg qualify as "local trains," which means many inexpensive tickets are valid on the route. Among these include the Schönes-Wochenende-Ticket, and the Rheinland-Pfalz/Saarland Ticket. Additionally, if you are beginning your trip in the Mannheim or Kaiserslautern areas, you can save even more money by purchasing a local transit ticket called the Ticket 24 or Ticket 24 Plus. These tickets are valid in the VRN local transit area, all the way to Wissembourg, for 24 hours. As of 2010, cost of this ticket was EUR 14.70 for one person, or EUR 20.50 for up to 5 people traveling together. An added bonus is this ticket, when validated on a Saturday, is valid until 3AM on the first following work day (e.g., Monday morning for a standard weekend).
The station itself is on the north side of town, about a 15 minute walk from the old town. Follow the posted maps (and the crowd), and you'll be fine.
Wissembourg is the border station between Germany and France. To the French side, a local train route connects it with Strasbourg. German trains arrive and depart here, too. They run along the Palatinate via Landau to Neustadt an der Weinstraße. The trains have immediate connections to Karlsruhe in Winden/Pfalz – don’t panic about the usual 2 minute connections, those trains stop on opposite sides of the same platform and wait for each other. Visitors to my hometown may find interesting that Wissembourg is considered part of the KVV public transport network and the trip can be done on a KVV Ticket.