atempted oil change

hi. my boyfriend tried to change the oil in our car and accidently drained the transmission fluid. now the car will not move even though it is showing that there is plenty of transmission fluid. we have a 2002 honda passport with a little over 100,000 miles on it. it is our only car and we are on a very very tight nudget so if we can fix it without going to a mechanic please let me know. thank you