Use the Add Widgets Panel to add widgets to a campaign. When the Campaign Builder loads, the Edit Widgets Panel is open by default. You can close and reopen it by clicking on its icon on the left side of the page. When the panel is open and automatic positioning is turned off, you can click and drag the header to move it around the work space and position it where you'd like it. With automatic positioning turned on, it will appear in the top-left hand corner of your workspace. Click and drag the panel's edges to re-size it.
Click on the Add Widgets Panel button at the top-left of the Campaign Builder.
Click on a widget's icon to add it to a campaign, or click and drag a widget's icon to place it in a campaign. When you add a widget, the Edit Widget window pops up so that you can customize the widget. When you're done making changes, click Save & Exit at the bottom-right of the Edit Widget window to close it, and the widget will appear on your campaign.
Use the Change Layout button in the top-right of the Add Widgets Panel to choose how it displays available widgets.