In the main window of Movies 13, you will be abel to create a new animation and add the GIF files that you want 

From the Options tab window of Movies 13, you will be able to set the Frame delay, number of frames or loops. 

Fom the Tools tab window of Movies 13, you can select the GIF Explorer, AVI to GIF, GIF to AVI Converter. 

In the AVI to GIF Converter window you must add the AVI files that you want to convert to GIF