After you've added the desired blocks to your layout, you may move, resize, delete, or change the options of the block at any time.

Moving Blocks – Click and drag the block. If you wish to move multiple blocks simultaneously, double-click on a block to enter Mass Block Selection Mode.
Resizing Blocks – Grab the border or corner of the block and drag your mouse.
Block Options (i.g. header image) – Hover over the block then click the block options icon in the top-right.
Deleting Blocks – Move your mouse over the desired block, then click the X icon in the top-right.

Telki, 2007.