Becasue I've installed the Ubuntu 18.04 LTS in my wsl, I click the icon to start.
1.Start wls2 and docker
# showing docker status
service docker status
# start docker service by root
sudo service docker start
2.Download the gitlab-runner docker image
Command: docker pull {the image name from gitlab}
For example:
docker pull gitlab/gitlab-runner:latest
3.Show docker images
docker images