No question is stupid - I haven't used SharePoint List forms much, so I'm having to walk through this too.
It looks like by default the repeating section doesn't have "Allow users to insert" enabled - right click your repeating section and under the properties you'll see something like the screenshot I've attached. Once you click the "allow" checkbox you can then click the checkbox that will display the "insert item" widget.
I went ahead and published my form after making these changes, and after I made sure I had all the required fields on my form (oops!) I was able to save multiple list items when creating a new item in the list.
However, I'm not seeing a way to actually edit multiple items (check a few items, select Edit only opens an individual item).