Diode-Bypass-Blocking

Hi All....I could really use some help on this. I have been asked to help figure out the wiring on some older Siemens 90 & 80 watt Panels, two of each. The wiring apparently has been rearranged by the owner (older gentlemen) and now he does not know how the wiring went. Apparently these panels also have diodes attached, I have never worked with diodes before, and don't have clue as to placement. I have been told there are two terminal blocks, a 6 volt and 12 volt. He would like the end result to be a series/parallel design. This system is in a remote area, travell will be very difficult soon (tomorrow), due to spring thaw. A terminal block I know has 6 wire placements, first three are negative, next three positive, but how would you connect a pair of diodes and what would be the direction of the current flow? I know I have not explained very well, but if someone had a installation diagram it would sure help.