HTCFirstSubmissionGuide
This is only a quick first draft for you to learn more on how to use HTCondor.
HTCondor Official Documentation
Have a look at the official User Manual on the HTCondor website.
It is very well done and explains all available features.
HTCondor Workshop Presentation
Every 6 months, there is an HTCondor workshop. Presentations are usually very helpfull, especially if you want to go into details of HTCondor (API, DAGMan, ...). You can find the agenda of the latest one here
For users, we recommend following this presentation, that should give you an idea of how to submit jobs.