An animation tile sheet is an image containing the complete set of frames necessary to achieve a specific animation using the
blitting method.
For example, this one:

Few days ago I stumbled upon a great script for Photoshop to generate automatically tile sheets like this.
RA Animation Exporter 1.2Download it and put the JSX in your Photoshop script folder.
The whole process is very simple, you just proceed like you wanted to create an animated GIF in Photoshop.

Then you will be able to launch the script going to Menu-File-Scripts-RA Animation Exporter v1.2, if it is not there, just click on browser and look for your JSX file. It will generate a single PNG containing each frame of the animation.
Just remember before to proceed create a backup copy of your work.
The script is not perfect, I tried to contact the author to try to fix it together but he never answered to my email.
Anyway, if you find a way to fix it please let me know.