How to create shadow in Photoshop

Blending mode: 

Choose a blending mode from the drop-down menu to adjust the darkness of the drop shadow. The blending mode Multiply can give you better results.

Drop shadow color:

Click on the color box to select a color for the drop shadow.

Set opacity of the drop shadow:

Adjust the opacity of the drop shadow with the slider or type the percentage value of the opacity in the cell. In most cases, 50% opacity is a good fit.

Change the angle of the drop shadow:

Rotate the angle spinner according to the light direction or type the angle value. You can enable "Use Global Light", to use the current setting for the global light source.

Distance:

Set the value, the shadow distance from the subject.

Spread:

You can increase the spread to make the edges of your shadows harder and darker.

Size:

You can increase the size of the drop shadow with the Size slider.

Contour:

Select a contour to how the shadow fades. Contour examples: Linear, cone, cone-Inverted, cove-deep, etc. In addition, you can customize the contour. Let`s say you selected the "Linear" contour. To customize the linear contour click on the contour editor then a pop-up window will appear. Here you can change the preset and adjust the curve

Anti-alias:

To smooth the contour enable Anti-aliased.

Noise:

You can add noise with the Noise slider. Increase noise to add texture or decrease noise to get a smooth effect on the shadows.

If you think everything is set up properly then click on OK.

Watch the following video.

 Learn how to create a real shadow, and a shadow as if the object is floating in the air.