Im working on ASPX-templates and need a solution to displays the images, that are created in Images folder in the CMS Desk?

Like this:

Images
Birthday
Birthday_Image_1
Birthday_Image_2
....
Christmas
Christmas_Image_1
Christmas_Image_2
....
NewYear
NewYear_Image_1
NewYear_Image_2
....


I need to display all the images or specific folder wise that is based on the user selection.
Kindly give a solution to fill the category drop down as well as show the image gallery.