Stuck in 1st GEAR!!!!

My car won't go into any other gear than 1st. I have an automatic transmission 1992 Honda Accord EX. When I turn the car on it is fine. Then a couple of seconds later, the D4 on the console turns on and the shifter button that releases the shifter clicks and I can move the shifter freely WITHOUT pressing the brake. It is only supposed to be released when you have your foot on the brake. The D4 green light stays on and when I drive it stays in 1st gear and kinda shakes a little. Does anybody know what could be wrong with my car. Thanks. Oh yeah. I tried the self diagnosis thing with the wire by the passenger kick panel and the green light blinks once real long then twice real quick. I'm guessing that is a code 12 right, or wrong. HELP!!!!!!