This paper describes a Project entitled "Divulgación de Recursos Educativos Digitales (DIRED)" (Divulgation of Digital Educational Resources) addressed to promoting specific educational resources and mobile apps for educational proposals through the institutional repository of the Salamanca University (GREDOS). We present a proposal for describing learning objects based on pedagogical information, digital competences and learning styles. We also suggest educational information for classifying useful mobile apps. To achieve this we focus on the use of learning-object specific metadata in digital repositories such as LOM (Learning Object Metadata). We study the metadata mapping necessary to adapt from LOM to Qualified Dublin Core, because this is the standard used in the GREDOS repository built with a DSpace platform. Finally, we present our implementation of Learning Object Description in the GREDOS repository.