Hi
1.
Make a developer account: https://www.e-conomic.com/developer
Grab a demo account: https://www.e-conomic.dk/regnskabsprogram/demo-alle
Connect the demo and the developer accounts: https://www.e-conomic.com/developer/connect
2.
POST an invoice including the lines: https://restdocs.e-conomic.com/#post-invoices-experimental-drafts
3.
Include your lines in the POST in step 2.
4.
You can see a demo of getting the pdf here:
https://restdemo.e-conomic.com/index.html?path=invoices-experimental/booked
"pdf": { "download": "https://restapi.e-conomic.com/invoices-experimental/booked/20001/pdf?demo=true"