Django web app database errors

I have a Django app with mongo and Postgres db. I was working with another developer that put the app in docker. I am not familiar with docker and would like someone that can explain it to me and how I can use it. I also have code that I need. to get merged with my docker app that has different db and need to be fixed. I need this work done today. A NDA would need to be signed to perform this work.