To edit information about a Journal (Editor, Conference) just double-click on it. New window will appear. In the window edit description, URL, abbreviation etc.
To edit a paper select it in the list, than press Ctr+ Enter or select Edit Description in the pop-up-menu.
Mo modify author, select the row in the author list and double click or press Edit. To import the pdf file and link it with the citation, press Add File, select file desired and press Open.