How do I show guides?

Guides must be enabled before they are displayed on screen.

Begin by opening a new document. 

Enable the rulers either by pressing "Ctrl + L" or "Ctrl + Shift + R".

Then you can create your guides: 

Creating a horizontal guide: 

Place your mouse pointer over the horizontal ruler and left click your mouse button. With the mouse button held down, drag your mouse onto the working area . Release the mouse button where you wish the horizontal guide to be added.

Creating a vertical guide: 

Place your mouse pointer over the vertical ruler and left click your mouse button. With the mouse button held down, drag your mouse onto the working area . Release the mouse button where you wish the vertical guide to be added.

Repeat these steps for each guide you wish to create.

Enabling and Disabling the guides.

Open the Layer Gallery, remove the check from the left sided check box next to the layer named Guides, or press num pad 1 on your keyboard to toggle the guide layer display.

Related article: Grids, Guilds, Snapping and Scale Line Widths