How Will I Get to Find Drug Rehabs in Post, Texas?

My dad left us with nary a goodbye. We just woke up one day and he was gone, along with a lot of his belongings. I know my parents fight, but I didn’t know that it was that bad. Since then, my mom has taken to smoking heroin. I really want to help her by getting herself treated. I already talked to her and she already agreed. How will I find drug rehabs for her?