jumped /dʒʌmpt/ is the past simple and past participle of jump. The written e is silent; /dʒʌmp/ plus /t/ makes the final ed sound like /t/. He jumped the queue and everyone noticed.
Jumped is spelled j-u-m-p-e-d: the base form jump plus the -ed ending. This spelling is the past simple form of jump, so it works on its own in sentences like He jumped the queue.
Jumped also serves as the past participle, so after has the same spelling appears again: nothing changes in form.
Say /dʒʌmpt/ slowly a couple of times and the spelling jumped will feel automatic.
A small pronunciation note
One small trap in this word: jumped is just jump /dʒʌmp/ with one written syllable more, no extra vowel letter. Write jumped, never jumpped or jumpt; the single e is silent and the d spells /t/ after /p/.