The Housing Choice Voucher program is funded by the federal government and run by Albemarle County.  The demand for vouchers is far greater than the number available, so the first step is to apply to the waiting list when it re-opens.  If you are awarded a voucher, you pay 30% of your monthly income toward your rent, and the voucher covers the rest.  The Office of Housing can refer you to other organizations to help you find a rental unit.