The easiest way to collect things in Eluma is through the Eluma Toolbar. On any bookmark you'd like to collect, simply click the "collect" icon 
. A dialog will pop up that lets you specify the title, description, and tags you want. You can also choose the location Folder where you want your bookmark kept. Alternatively, you can drag a bookmark from your browser to Eluma by clicking on the icon in the browser's address bar and dragging it to Eluma.
Eluma Tutorial
