Beginner needs help saving a transcription

Hi, I'm a brand new Citizen Archivist and just completed transcribing my very first page and it didn't save. I read through everything I could find as far as instructions and tips before I started and felt pretty confident that I did things correctly. I chose a page from a large mission - I scrolled through all of the completed pages until I found one that was available to transcribe, clicked on "start transcribing" and began. Periodically, a green "Saved" with a checkmark would flash at the bottom left, and when I finished, I didn't see anywhere to select "Done" or "Complete", and the button to complete and publish wasn't clickable, I assume because the entire mission has to be complete before it can be published? So I clicked the "Close X" in the top right corner. I got a warning that the document was not saved and if I closed now, I would lose all of my changes. I canceled that, and looked again for something that I could select or click on that was more official to save the page or complete the page or something, but there was nothing like that. I watched the green "Saved" with checkmark update again and thought this had to be safe to close, so I went ahead and clicked close again and ignored the warning that popped up, thinking maybe that meant the entire mission wasn't completed or something. Well, all of my transcription was lost and that page reverted back to "available" to transcribe status and it was blank. Can someone please tell me what I'm doing wrong? I know I can work on just one page of a mission at a time, right? How do I save that work?

I'm excited to get started, but honestly feeling very frustrated right now.

I would like to suggest a more thorough "walk through" for beginners of how to complete a transcription of a page from start to finish that includes closing / saving. I haven't been able to find ANYTHING that explains the proper way to close a transcribed page and to ensure your work was saved.

Thanks - Dean