If you are a citizen of a member state of the European Union or of the European Economic Area (Iceland, Liechtenstein and Norway), you do not need a visa or any other previously obtained documentation. A valid passport or identity card allows you to enter Spain.
Once in Girona
It is not necessary to apply for a residence permit. The only documents necessary are a passport and/or identity card.
It's compulsory to go to the Foreign Office (Oficina de Extranjería en Girona) and apply for the Certificado de Registro de Ciudadanos de la Unión in order to register your stay in Spain in the Central Registry of Foreigners during the three months after your arrival. You´ll get also a NIE number .
For Further information and the application form, can be found in the following link