Once you have added your picture to the document you may want to move it to a new place, fix it in the place it is in, or make it bigger or smaller. These actions can all be done on screen with the mouse so you can always see what is happening.
To move a picture around the page:
Pictures are always pinned to the cell/text layer of the document, so that they move if rows and columns are inserted or deleted. You can tell that the picture is pinned because the top left selection handle appears solid red, and the others are in outline.
You may want to pin the bottom of the picture as well, for example if you are adding a border to an area of document and think you may want to insert some more rows in the middle of the section.
To pin pictures:
You may want to unpin pictures so that they stay in the same position on the page, rather than floating with the paragraph or cell to which they have been pinned.
To unpin pictures, double-click the top left selection handle so that it is an outline rather than a solid square. If the bottom right selection handle is solid (and therefore pinned) you should double-click that as well.