This article will teach you about guides and snapping functions.
Guides
Guides and snap to functionality are now available in the Ad Builder. Guides can help you easily position layers or elements on the ad canvas. Guides do not appear in the ad preview or when served, but are lines that float on your canvas. You can move and remove guides.
Show or hide guides
Choose File > Settings > Show > Guides
A check mark indicates that guides are enabled.
Place a guide
Drag from the horizontal ruler to create a horizontal guide.
Drag from the vertical ruler to create a vertical guide.
Move a guide
Position your pointer over the guide (the pointer turns into a double-headed arrow).
Drag the guide to move it.
Remove guides from the canvas
Drag the guide outside the canvas window.
Snapping
Snapping helps with exact placement of layers/objects on your ad canvas. When snapping is enabled Smart Guides appear automatically when you move objects.
Enable or disable snapping
Choose File > Settings > Snap To. A check mark indicates that snapping is enabled (click in box to check).
Specify what to snap to
Choose File > Settings > Snap To, and choose one or more options from the submenu:
Guides: Snaps to guides.
Layers: Snaps to the content in the layer.