One more thing .. at the save part, you will not get the Sharepoint folder unless you have configured the save there.
In my case, I was prompted with the My Documents folder by default.
To configure a folder, go to Your List -> Settings -> Form Library Settings ->Advanced Settings
- enter the destination document url in the "Custom Send To Destination" section.
- you can also force it to use the browser, instead of the InfoPath client by choosing "Display as Web Page" in the "Browser-enabled Documents" section.
For more advanced stuff, you can add a save button and concatenate a filename from the entered fields and display an alternative view on success.