HEC publishes training material from it's live courses on the HEC website here: http://www.hec.usace.army.mil/training/materials.aspx. I would recommend downloading the HEC-HMS training material and reviewing lectures and workshops. Aside from the training material, the HEC-HMS User's Manual, Applications Guide, and Technical Reference Manual are all good resources. These are available on the HEC website here: http://www.hec.usace.army.mil/software/hec-hms/documentation.aspx.