This is where things get a little tricky. Children learn by example, and they are always watching their parents and other adults around them. They learn by doing. If they see the adults around them using good manners and proper behavior, then they in turn learn the same behavior.
Young children need to learn to ask before touching things, especially Altars and Tools. I'll give an example on one way to teach your child about asking first and magickal ethics. Say they bring their favorite stuffed toy with it's head torn off. Ask them if they want you to fix the toy, or do they want you to just hold it. Ask if your child needs to be held. Always ask before you do something. It helps teach your child good manners.
My son, Aiden, is just learning how to use manners. We've finally mastered the concept of "please" and "thank-you". Now we're working on "I'm sorry" and "you're welcome". But he nearly always asks me before he touches things. It'll be awhile yet before we fully master that concept.
Another thing to teach your young child, is how to vent their anger and frustration in acceptable ways. I've been known to give myself a time out before. The way Aiden and I deal with his temper is by acknowledging his anger, and then finding a way for him to use his energy constructively.
It's funny, because I used to refuse to acknowledge his temper tantrums. When he'd throw a fit, I'd ignore him, because I thought that if I catered to his every whim, he'd throw a fit every time he wanted something. But then I realized that by ignoring him, I was teaching him that his feelings didn't matter to me and that they were worthless. So when Aiden throws a fit now, I first tell him that he must be pretty angry with me, and then I try to redirect his anger. We've drawn pictures with the crayons, jumped up and down on the laundry, and I'm sure once the autumn leaves fall again, we'll probably be jumping out our anger on the leaves.
There are hundreds of techniques out there on how to teach and discipline your children in a positive, non-threatening way. Try looking in the Parenting section in your local bookstore or library.