If you have a lawn, you can add grass clippings. Those are great sources of "greens". Used coffee grounds work well too.

As long as they are out in the weather they will be ready by spring I collect and shred about the same amount have a big wire bin to hold them the next spring I mulch every thing that needs it in the veggie garden and till the rest into any open beds keep some for starting my compost bin when the grass clippings start. The pile will shrink by about 1/3 during the winter. The worms love it my garden has the biggest night crawlers and red worms too.