Here you can go to DHS site and apply online. A social worker will then call you and go over eligibility, requirements and types of fostering. They will do background checks, home visits and classes/training. My cousin did a foster and ending up adopting the infant. My nephew went through foster system as well.

Foster care mom since February 2015

Different states have different criteria. Visit the states department of family and Children services and there will probably be information. Usually you contact them and they will set you up with a social worker if you meet the criteria.