You can browse Docker repositories in the user interface and inspect the components and assets and their details as documented in Browsing Repositories and Repository Groups.
When using the docker command line client, or any other tools using the repository manager indirectly, the common structure for commands can be:
docker <command> <nexus-hostname>:<https-repository-port>/<namespace>/<image>:<tag> docker search <nexus-hostname>:<https-repository-port>/<search-term>
a docker command such as
the IP number or hostname of your repository manager
https port which ultimately directs to the NXRM docker registry https port in the repository connector config, or that of a reverse proxy https connector which proxies the docker registry plain http port
the optional namespace of the specific image reflecting the owner, if left out this will silently default to /library and utilize Docker Hub
the name of the Docker image
the optional tag of the image, defaulting to latest when omitted
the search term or name of the image to search for
The most important aspects are to know and use the correct hostname for the repository manager and the port for the desired repository or repository group.