The plug that went directly to your old sealed beams for the headlights will plug right into the silvia lights. As for the side markers, it is up to you on how you want to wire them. For my last sil fronted 240, I got a little creative and jumped the rearmost lights in the corners to the turn signals in the front (ie they only turned on to flash with the front turn signals) while I just ran the stock wiring from the fender to the forward lights.

If you're unsure about what any wire does, grab a multi-meter or even a simple test light and test the wires. Also, if you're missing any of the bulb holders, they can be scavanged off of pretty much any Nissan that has 194's as bulbs for side markers. Just pay attention to the pattern for how they slot into the physical housing.