Well, I don't know if this will help, but.....
Predication requires a subject and a predicate. The subject is the sentence part about which the predicate tells something, and the predicate is the sentence part which tells something about the subject. That would seem to be an impossible set of definitions, except for the fact that subjects and predicates ALWAYS come as pairs (whether they are compound or not). You can't have one without the other.
A simple predicate is always and only a verb or verbs.
This is classic, basic Reed-Kellog. Predication is not a part of a sentence. Rather, it is a process, like modification, complementation, subordination, duplication (appositives), and coordination. A predicate, whether simple or complete (including all modifiers and complements), is a part of a sentence.
I hope this helps.