1991 Ford F-150 getting codes

Ok this is very simple first find you diagnostic connector and the single connector next to it. Now get a test light and paper clip and follow the diagram below. Use the test light inplace of the volt meter and the paper clip to jump from the single test connector to the signal input as it shows. Then turn the key on and count the test light blink. It will blink short pause then blink again, so it is blinks 1 then 2 that is 12. Then it will pause longer and go to the next code. Use the first pic that includes the battery. Yes the test light is connected between the possitive of the battery to the diagnostic connector as shown.