How can I get a free tummy tuck? I had 5 c section and stomach has a flap at the bottom.

Thank you for sharing your question.  Elective surgery like a tummy tuck is never free as there are associated costs outside of the surgeon's discretion, namely anesthesia and facility.  You may be able to seek out a local plastic surgery training program where costs would be lower, however. 

Thank you for the question . What patients may not realize is how much “overhead” is associated with performing good quality and safe elective plastic surgery. In other words, there are significant expenses, outside of surgeons fees, associated with these types of operations. Therefore, it will be unlikely that “pro bono” elective plastic surgery will be available to you. Plastic surgery teaching programs may be an option.
Plastic surgeons offices can point you in the right correction when it comes to “credit” companies that work with patients seeking surgery.  It is always in patients' best interest to achieve a certain degree of financial stability prior to undergoing elective surgery of any type. Patients should also keep in mind that additional surgery may be necessary in the short or long term, following the primary procedure that is being performed; this additional surgery may be associated out-of-pocket expenses. Again, best to achieve a physical, emotional and financial “stable state” prior to considering elective plastic surgery. 
You may find the attached link, dedicated to tummy tuck surgery concerns, helpful to you as you learn more. Best wishes.