In the Pages panel, right next to the page color icon, uncheck the check-box “Exclude page color”. Now your page color will be visible on products. Later, I will change this so its not checked by default.
Attention: Another way of making the background orange is to add a panel object as big as the page, make it orange and move the panel object to the back if its in front of some other object. Its often possible to solve things in Fatpaint using different aproaches, you just need to be a little creative. With the selection tools, move objects back and forth, inside eachother, set blend mode, etc. you can accomplish many things.
The problem with image uploading not working, I have no idea what is the problem. Have you also tried to upload from the File manager (Start it from the “File” menu)?
What OS and browser are you using? If you are not using Google Chrome, try using it and see if it works there.
Let me know if you still have problems.