You must go to the Spanish Embassy to get the VISA application form and confirm you have the documents needed for the procedure to be completed.
List of documents required
1. Application form
2. Three passport size photographs
3. Valid national passport
4. Proof of sufficient financial means: evidence that you have sufficient funds to support yourself here and to go back to your country
5. Medical insurance
6. Official certificate from Police records
Once in Cartagena, you will have to get another document (Permiso de residencia de estudiante).
I love UPCT for the architecture of its ancient buildings and especially the School of Business where I study. I have never seen such an Erasmus group. I like meeting people from Europe. Cartagena is, in my opinion, a small paradise.