closeddocker: “build” requires 1 argument. See 'docker build --help'

So I've been getting into docker and for this, I've been following the docker documentation.So for my doubt, I've been specifically following this instruction for creating a docker image : But I keep on getting an error while following it exactly, here are my dockerfile and build command and the error:

My dockerfile :

FROM        ubuntu:14.04
RUN         apt-get update && apt-get install -y redis-server
EXPOSE      6379
ENTRYPOINT  ["/usr/bin/redis-server"]
Docker build command :
$ sudo docker build -t myrepo/redis
Error:
docker: "build" requires 1 argument. See 'docker build --help'.
How to remove  error ”docker build requires exactly 1 argument”. Can someone help me solution.
FROM        ubuntu:14.04

RUN         apt-get update && apt-get install -y redis-server

EXPOSE      6379

ENTRYPOINT  ["/usr/bin/redis-server"]
FROM        ubuntu:14.04
RUN         apt-get update && apt-get install -y redis-server
EXPOSE      6379
ENTRYPOINT  ["/usr/bin/redis-server"]