Can i become a foster parent if i had an open case with dcfs but now closed, children returned.?

my kids we taken and later returned after i completed drugs test, and parenting clasess i want to become a foster parent im on ssd im bipolar due to ual harrasement at work, i will be taken care of my kids for the next 15 years i babysit alot and i want to help i was also a foster child. my sister made allegations but the courts found me to be mentally stable im not on meds i want to know where to start please help me