Drag and Drop not appearing in widgets panel

I’m a 10-day old blogger using wp 2.5.1. The 2 panel drag and drop option does not appear in the widget panel on my wp-admin page; only 10 predetermined widgets are available. I understood the 2 panel drag and drop option was included in the 2.5.1 wp version. I am using wp & K2 theme with 3 panels. Any suggestions on how to install/activate the drag and drop option. Best wishes!