The following requirement must be fulfilled:
The desired photo is opened for editing in the Editing Photos screen. 
To add an effect to a photo, proceed as follows:
1.
Click the Modify button on the lower task bar.
à
The Modify window is opened.
2.
Click the Effects tab.
à
Color and editing effects are listed.
3.
If you want to see a preview of an effect, place the mouse pointer on an effect thumbnail.
à
A preview of the result is displayed in the Editing Photos screen.
4.
Click the respective thumbnail to actually apply the desired effect.
à
The effect is added to the photo.
è
You have added an effect to a photo.
See also
General Editing of Photos

Adding Effects to Photos