With the above suggestions at what point are you stock. Please share screenshots providing more details. And a full explainer where you are stuck.
You can setup shipping using: https://support.google.com/merchants/answer/6069284?hl=en
And reprocess the feed. If you are using content API you can reprocess using the steps here: https://feedarmy.com/kb/how-to-reprocess-content-api-in-google-merchant-center/