Nearly all hospitals have parenting classes. Also look in the yellow pages and on the Internet for classes. Love and Logic offers workshops as do other organizations. Love and Logic for Toddlers, written by Foster and Kline is a really wonderful book for learning parenting.
You do need to choose some way of dealing with your toddler/preschooler and be consistent with it. And you need to seem confident with your child even tho you aren't feeling confident. Firmness and consistency are the most important parts of parenting no matter what method you use. Choose a way to discipline for now and then you can change it once you have more information.
Try writing about the way you parented your older children and "guess" about what worked or may have not worked. This may help you sort out some specific issues.
As to the issue of respect, what is most important is to treat the child and everyone around you with respect. Children learn respect from watching the adults in their life be respectful. Respect means disciplining without anger and acknowledging the child's feelings. Discipline their behavior and not their feelings. Allow your child be be angry and teach them how to respectfully express that anger.
Always talk with your child in a respectful way. I became more aware of this idea when I was visiting a friend with a 2-3 yo. I was there to help her with some sewing. He kept interrupting us. I'd been in similar situations and heard parents yell at the child blaming them by saying something like, "you're in my way. Get out of here!" In this instance my friend said, still in a frustrated tone of voice something to the effect, "Joe, I'm having a difficult time here. Would you please go to the family room until I'm finished. I'll come to talk to you when I'm done." What a difference! Joe went to the family room. I noticed that he came back to the door a couple of times to see if we were still sewing but he didn't interrupt.
As to the teen/adults it's not too late to teach them to respect you. We all have consequences for our behavior all of our lives. First have a talk with them, individually or together for those who live in your home or even individually for them too and tell them what sort of behavior is respectful and what is not. Then tell them what you will do when they are disrespectful. Then follow thru by doing it. It may take them quite awhile to learn but if you're able to be consistent they will learn.
When I started doing this with my adult daughter, matters got worse. Seemed like we were always fighting. Then I realized that what was most effect was to leave her home immediately when she violated my boundary of respect. I lacked confidence at first and tried to convince her that my boundary regarding respect was reasonable. This only created another thing to argue about. But after I had just said goodbye and left several times she got the message that I was not going to continue in our old pattern of relating.
The first few times I left, I hesitated, hoping that she would catch on and regroup. Nope! Didn't happen. The most effective way of doing it is to calmly say goodbye before I'm angry and walk out the door.
A known result of changing ourselves and the way we act is for the other person to expend lots of energy trying to convince us to change back. We have to keep our energy up to resist their push to change back. Build up your confidence and self-esteem by taking care of yourself. That's a whole other task. Taking a parenting class will help with gaining confidence. Talking with people who will listen to you vent is another helpful way especially if they understand what you're trying to do.
I also recommend individual counseling for yourself. I was in counseling while I was working out my solution for the disrespectful pattern of relating that my daughter and I had developed. I had a lot of anger at myself and with her to deal with. I couldn't change the way she felt and acted but I could change myself which then enabled her to react differently.
When something happens that causes me to feel like a failure as a parent I remind myself to think about the successes I also had. Think of the ways in which you are proud of your older children and tell them about your feelings of pride. Start with observing individual incidents and say, "I'm proud of you for doing that." If you haven't been doing that already they will react with confusion or even anger. Just keep up the positive comments and they'll begin to accept them.
