You can run it with a command like this (I'm on windows):
docker run -it -v <model file path>:/stable-diffusion/models/ldm/stable-diffusion-v1/model.ckpt
-v <outputs folder>:/stable-diffusion/outputs
-v <inputs folder>:/stable-diffusion/inputs
-v <cache folder>:/root/.cache
--gpus all knightley python /stable-diffusion/scripts/txt2img.py --W 256 --H 256
--prompt "a horse wearing a top hat"
assuming you build the image and tag it "knightley"
