Please use https://github.com/GChristensen/scrapyard/issues, but not ratings to solve problems. Low ratings will help a little.
1. You should have been choosen the shelf/folder where you saved them in the popup window.
2. They should be in these folders.
3. The addon is accessible through the sidebar. You can open it with the dedicated Firefox button or by pressing Alt+Y.
4. If yo do not press Alt+Y, you need to choose Scrapyard in the sidebar through the sidebar drop-down menu at its heading.
Does this solve your problem?