opencockpits master card j2 output qestion

hi guys
i have dicided to go with opencockpits on interfacing i am reading about how to connect inputs and out puts there is one part of the outputs that i dont understand and wondering if some one can help out i dont have the card yet so it will be a bit harder
j2 are the out puts and pin 1 is the possitive and 2 negetive say i whant a push button when presset a led to light the push button will be a input on the j3 first group 001 and its ground how do i conect the led to j2 so it will light???i read a titorial on the sight but did not understand it do i use one of the out puts and groung from j2 or the 5volt positive and one of the out puts on j2???

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