Give Engels' Principles Of Communism a go.

Parenti's Blackshirts And Reds is an engaging and straight forward read, although I suppose that's not really theory.

And yes, I also have a hard time with a lot of this stuff as I have no background in philosophy or really any academia at all. I think we have a great resource right here on hexbear, there are plenty of well read folks here who I'm sure would be happy to help out and answer any questions you might have on specific things you're struggling with.