Ubuntu - Can't join docker group

[20gt]

This is in Ubuntu
steve@steve-P5E:~$ sudo groupadd docker
groupadd: group ‘docker’ already exists
steve@steve-P5E:~$ sudo gpasswd -a ${steve} docker
gpasswd: user ‘docker’ does not exist

what am I doing wrong?

[20gt]

ANSWERED

$ sudo usermod -G docker -a ‘steve’

it didn’t error so i think that did it