The FAFSA an upcoming academic year will open on the October 1st PRIOR (i.e. the 2019-2020 FAFSA opens October 1, 2018) at https://fafsa.ed.gov/. You and your parent or guardian will fill out the FAFSA every academic year that you are in a college or university.
General FAFSA questions and answers can be found here through StudentAid.ed.gov
State FAFSA filing deadlines can be found here.