The Sandbox image will export the API on port 8080. Sandbox also expects a 'main.js' file which describes the Sandbox API. Sandbox is installed at /usr/local/sandbox in the container and will look in that location for the main.js file.
The following command will start a sandbox container, expose port 8080, and mount a 'main.js' file from the current working directory into the sandbox working directory.
docker run -d --name sandbox -p 8080:8080 -v $PWD/main.js:/usr/local/sandbox/main.js svickers/sandbox:1.0