P.S: You can use this for Letters to
Here's a tutorial on how to make a .gif like this one below:
1. Open up your picture in Photoshop. Add the coloring, textures or whatever you usually add, and once you’re done merge it all onto one layer (right click - merge layers). Then duplicate the layer (right click - duplicate / CTRL + J), and now you have two layers.
Make sure you’re on the duplicated layer, and head to Filter - Blur - Motion Blur. The Motion Blur window will appear, and change it to these settings below:
2.Click Ok, and go to Windows --> Animation. This enables the animation bar, and click on the button below on the upper right hand corner.
3.Then select "Make Frames from layers", You will now have two frames in your animation bar, the first is your normal picture, and the second frame is the motion blurred one
4.Change the settings to the one below by clicking on the black inverted triangle next to the number of seconds.
5. And now you’re done! Save the gif by going to File - Save for Web and Devices. Make sure to change the looping option to Forever.