Use the straighten tool along top or bottom edge of photo template.
Check the angle in the angle box on presets bar and WRITE that number down.
Choose the hand or move tool; then make sure your photo layer is selected.
Select your rotate tool (image>free rotate or control r on the keyboard). Direction: right; All Layers: unchecked; Degrees: Free and enter the number you wrote down in the box. Click okay
Lower the opacity on the photo layer and move the picture over the photo template. If you need to resize (and please only resize down, not up. In other words, don't ever make the photo larger than it was.) choose the pick tool and set mode on preset bar to scale. Left click and hold on of the corner nodes. Pull to adjust size but so picture is still outside the photo template.
Select the magic wand and photo template layer. Click on the photo template.
Click on the photo layer and raise the opacity to 100. Then Selections>Invert or control shift i on keyboard. Press the delete key on keyboard.
A photo at the correct angle.
Template used is by Manda Girl.