How my changes can take effect on Discourse with docker

I think that OP is trying to make custom changes in the code. Your best option will be to fork discourse repo and then make changes on github.

And the use this code to have your production site pull from your repo:

https://meta.discourse.org/t/how-to-install-my-customized-repo-of-discourse-on-production-server/23364/5?u=abdul_munim_zahid