Red and green are line 1. Your box outside (the Network Interface Device or NID) should have red and green screws or be marked with an R and G.
Black an yellow are line 2. Yellow should be connected to the second red screw, black to the second green screw.
On your inside phone jack, red and green are typically connected to the top two screws, black and yellow to the bottom. I'm sure you could find a wiring diagram via google that would be helpful.