You can use a wide range of public or private buses/coaches from the Airport Terminals to Dublin City. It is best to have your route planned to get you closest to your accommodation. Details of the pick-up and drop-off points are available here. If you are arriving late at night, we recommend you use a taxi. These are available outside both terminals. The cost will depend on you final destination. All taxis, by law are metered.
You can find transportation information here:
https://www.dublinairport.com/to-from-the-airport/by-bus/dublin-buses