The easiest way to get around is on foot. The city is very compact and walkable. From the central station it’s a 10 to 15 minute walk to the Grote Markt.
If you want to go further away, then take a bike. Within no time you can reach everywhere in the city. Both the city and the surrounding area have a wide network of bike paths.
Don’t feel like cycling? Take public transportation (‘Openbaar Vervoer’/OV). Groningen has three stations: Hoofdstation (Central Station), Groningen Noord, and Europapark. As a tourist you can purchase a disposable chip card. Remember to check-in and check-out when entering or exiting the train or bus. You can plan your journey through www.9292.nl. Purchase a chipcart at a supermarket, central station (vending machine) or bookshop.