Convert an already existing github workflow and running it on a docker container

I am new to using non-basic docker images (alpine basic image for example). the one i need is the latest Ubuntu with windows PowerShell on it. I am referencing images from the following site on Docker Hub: Docker. this one is the one I am using for my docker file:
FROM: lts-7.2-alpine-3.14m (I put this at the top of the line in the dockerfile)
But I get multiple errors all of which is most likely due to the way I have everything set up

With all of the online help, I an specifically am looking for a standard procedure on how to take an already existing github workflow which is in a yaml, then changing it to run in a docker container. I used the github examples as guidance but they really do not give instructions for what I need.

Here is a code snippet of the yaml file:
runs-on: ubuntu-latest
image: dockerfile

I used the following dockerfile from docker hub: Docker

this is the dockerfile: