My daughter is a foster parent. Call your local Department of Human Services or Child Protective Services and tell them you are interested. They will get you started on the classes you need to take. Also, there's an extensive application process which your background is checked along with your home. You will need to provide a list of people they can interview to ask if you'll make a good foster parent. Also, the classes involve learning about the various problems you will face with children who have been neglected or abused. Be prepared to testify in court if parental rights are removed from parents permanently. There state paid money to help with the costs of taking care of them but it's not really enough. You can count on paying out of your own pocket.
Before you go into the foster system ask yourself if your ready for that. I know people who have been foster parents who wanted to foster to adopt. Though they knew their kids they got may be taken away, they loved them with all their heart, and when the government put them back with their crappy original parents, they were completely heart broken. Leaving a room filled with toys and noone to enjoy it. Its a difficult thing. If you want kids the better option is to just adopt...because the heart ache in my opinion is just too much...I hate to see kids that are safe with a foster parent be sent back to someone who lies and drinks...If you have any questions I'd be glad to answer them about the foster care before you do this.