How I can sue the father of my 2 children for child support?
You need to visit the local child support agency and get forms which you will return when they are duly filled. They will organize to enforce the order. Read more on http://singleparents.about.com/od/statebystateresources/p/child_support.htm.
Google just what you said add lawyer and and broke you wouldn't believe what comes up! Sometimes free lawyer. Lawyers get you more money and most times guys pay for that to!
Talk to a lawyer.