i'll try to explain it the best way i can... preterito perfecto is a way to conjugate a verb, and it used for actions that happened in the past... for example you use preterito perfecto in this sentences:
it has rained a lot this year
i have worked like crazy
things that happened in the past but they kind of still last in the present
dude that translator really doesnt help all that much. it doesnt conjugate or anything, it just literally translates the words. like the word 'washington' would be translated into 'washing' and 'ton'. it kind of sucks but its still kind of usefull