Open the New dialog box from the File menu (Ctrl+N), select Photo in the Preset drop-down list, and select Landscape, 8 x 10 in the Size drop-down list.
Note: The only problem with the presets is that they all have a default resolution of 300 ppi, which is not necessarily required when actually printing photos.
Enter 213 ppi (enough to print on high-end printers) in the Resolution input box, then click the Save Preset button to open the New Document Preset dialog box.
After entering the appropriate preset name, select the preset parameters that suit you (generally not necessary, it is recommended to select all) and click OK.
The new custom preset size will appear in the Preset drop-down list.
If you want to delete the preset size, select the preset size to be deleted and click the Delete Preset button to delete it.
