Drag and Drop
You can choose an element either by clicking on it on the canvas or in the layer list. Once a layer is selected, you will see a drag control. Click and hold your mouse and drag the element to the position you want.
While dragging, the layer will snap to the edges of the canvas and to the centerpoints of your canvas.
Move elements with your keyboard
Use the arrow keys of your keyboard to move layers in 1px intervals in any direction. Hold the shift key simultaneously to move them in 10px intervals instead.
Use exact positioning
In the Arrange settings, you can set an exact position for your element.
Align layers
Use the alignment options to line up your layers relative to your canvas or to each other.
If you select a single layer, you will see options to align it to the canvas' center horizontally (center) or vertically (middle) in the dynamic toolbar at the top of the canvas.
If you select two or more layers, you will get even more options to align them to your selection's shared top / bottom / left / right border, or on its horizontal or vertical center axis.