I would highly suggest some of the Paul Harris books. They are available on Amazon. They, along with working a senior P6 user who was a contractor, helped me immensely. The videos and web training are just very high level and not very interactive. I have a link to a bunch of his books on my site, but you can go to Amazon as well. I would use the books in conjunction with the user manual on docs.oracle.com. The user manual is more of a seek & find as where Paul's books build on your foundation level as you progress through the topics.