I have found this blog http://transmississippian.blogspot.com/ to be helpful concerning events in the Trans Mississippi Theater, book recommendations, etc. The author's posts are intermittent as she is a prof at Rogers State University, Claremore.
... That's about it. I know nothing. Where do I start? Preferably something in the form of a Complete Idiot's Guide or something to where I can learn terms, weapons, important figures etc.
... I offered McPherson and Foote as overview starting points. The OP has clarified his/her goal in terms of learning battle tactics. I'm not sure what to offer here.
@Pat Young has offered some good stuff and I suspect James N. may have some insight here, if we can scare him out.
However, I believe newer editions may have a different title. For basic information about weapons, tactics and strategy Jack Coggins' book on the war - which I think has also already been suggested - is outstanding. If it helps, there IS one of those Complete Idiot's Guide(s) to the Civil War.