"Guides" are non-printable lines serving for mark-up and object alignment.
Officially, Photoshop Elements can only use existing guides (so called, "guide presets"). To create guides of your own, you run the "Guides" script and choose an appropriate command in the dialog box that opens.
To add just one guide, apply the "New Guide" command. Then, in the "New Guide" dialog choose the guide orientation (horizontal or vertical) and define its position (distance from top left document corner) as it is shown on the screenshot 1.
Important! If you don't specify "px", "in", or "cm" in the "Position" field, the program uses your default units selected in the "Preferences" dialog.
The "Guides from Selection" command creates up to 4 guides based on the current selection (fig. 2).
The "Find Center" command adds horizontal and vertical guides at the document center (fig. 3).
The "Mark Margins" command creates four guides on each side of the document in order. You only have to specify the distance from each guide to the nearest edge.
Unfortunately, Photoshop Elements won't allow you to adjust the position of created guides. Be sure, to place them correctly straight off.
Also you can't discard an individual guide. You either hide (View > Guide Presets) or delete all the guides by double-clicking the "Clear Guides" command (fig. 4).
