Anyway, uploading to OwnCloud with Cargo Dock is the same procedure as copying files locally. You have two panes. In one pane you open the source folder, in the other pane the destination folder (in this case on your OwnCloud). Tap and hold on a file in the source folder to get into selection mode and select what you want to upload. Then select "Copy" from the menu. For downloading, do the same, just vice versa.