Really surprised you haven't had an answer to this yet.
1) The buttons on your editor, the one right next to the broken link and before the smiley face allows you to upload an image to where ever you want it to be. This is the "Insert or edit image" button. It comes up with the upload dialogue, which has a really poor visual impact for newbies, the actual upload button "Browse Repositories" is just not clear enough I suggest. Should have a name like "Select image" or similar.
2) The limitations of the Atto editor are becoming the stuff of dreams, really bad dreams.... but the changes to tables are even worse. You have to format the table as best you can when you add it to the page then enter the HTML editing screen and make whatever changes you want, or it may be possible to create a standard table in a text editor and copy and paste that into your document when you want one. Unfortunately, HTML Tidy might have something to say about it, but give it a try. The alternative is to use TinyMCE as your preferred editor, I do.
viel Glück.