Aviza there are a TON of books about creating boundaries available to you through your public library as well as free articles and blogs about creating boundaries online via a Google search.

The way we create boundaries with each other is stating what our needs and expectations are to the other person. It's up to that other person, whether or not they will respect your needs and meet your expectations. We need boundaries in every area of our life; work, family, friendship, dating, school.

I am nearly 50, and I still practice creating boundaries with people because it's difficult to do when your self-confidence is low and when you attach your self-worth to external validation from others, and are codependent.

You can literally type this in your Google search for results, "How to create boundaries with..." and multiple search results pop up with different relationships.

From Psych Central's library of resources:

10 Way to Build and Preserve Better Boundaries