For paid jobs at Spanish Administration such as CSIC you should first check the procedures for recognition of Professional Qualifications (Regulated by Directive 2005/36/EC) and Recognition of foreign Higher Education qualifications (equivalent to Spanish university Grado or Máster degrees) that give access to a regulated profession in Spain.

For employment offers you can visit http://administracion.gob.es/ or the CSIC homepage http://www.csic.es (training and employment). All offers for CSIC centres are published here.

Once a call is opened, you have to complete an application form and send in your CV provided with credentials (true copies of degrees, contracts, publications, training, etc.). 

Please check the https://www.csic.es/es/formacion-y-empleo/formacion-de-personal-investigador to see funding possibilities in Spain