What am I supposed to fill in the configure site forum in Drupal site?
Thanks in advance for your help.
This is really something that has nothing to do with Docker. It is in the General Discussions category, so I don’t mind it to be here, but this is a question which would be better asked on a Drupal forum where you can ask about how Drupal works and what parameters do what. The picture you shared shows a standard Drupal installation page which would be the same with or without Docker. By the way the parameters are really straight forward so I am not sure what the issue is here. Sicne it is not a production website, you can retry it any times, so there is no risk of filling the form and making a mistake then trying again if you are not sure what those parameters are.
Update
On second thought, let’s turn it into a Docker question:
If you set the required parameters of a Docker image, you can usually install it automatically. First step is reading the official Docker image’s description
https://hub.docker.com/_/drupal
And second, in case of Drupal, try Drush, the command line interface of Drupal: