Animated Rain Help

I don't know if theres already a post for this type of rain effect, but i want to learn how to make this animation.


Like this:                                                                       And/or this:
                                                                                          
                                                      

icon made by colleendetroit                              icon made by rainbowgraphics 

I have Gimp2 and Photoshop7

I'm still new to making my own animated icons. Simple instructions are much appreciated. :)