Questions to Process Theology

I am interested by the process theology but i have the questions. English is not my native language, exuse me if i have mistakes.

What does process theologians mean when they say "God isn't omnipotent"? Do they mean "God can't desire something, but can do everything he desires"? Or they mean "God can desire some thing, but can't do that"? Can God wish to do something that contradict with his nature? As example: The Nature of God isn't allowing to control the someone or something to prevent evil. Can God desire to control? Or He can't desire to do this?.. If God can't desire to control (prevent evil) - He doesn't desire to do this ---> He isn't Omnibenevolent (??) If God can desire to control but can't do control (prevent evil) - He is weak/He has external constraint. But if i am not mistaking... God haven't any external constraints by the process theology. I don't know Thomas Jay Oord views on this questions, but i want to know) If any process theology followers are here - please answer to me)