Horizon 2020 Online Manual
http://ec.europa.eu/research/participants/docs/h2020-funding-guide/index_en.htm
Proposal Submission Service User Manual
http://ec.europa.eu/research/participants/data/support/sep_usermanual.pdf
Guide on proposal submission and evaluation
http://ec.europa.eu/research/participants/data/ref/h2020/grants_manual/pse/h2020-guide-pse_en.pdf
Other H2020 reference documents
(rules for participation, guides for applicants, proposal templates, evaluation forms, etc)
http://ec.europa.eu/research/participants/portal/desktop/en/funding/reference_docs.html
NCP network
http://ec.europa.eu/research/participants/portal/desktop/en/support/national_contact_points.html