Grey

Hi All, Forgive me I am very new to video editing and need your help. The rendering system that I use creates lots and lots of images assuming that they will be played back at 15fps. I presume that each image is a frame. How can I set the speed of the playback so that the video created from the images plays at 15fps?? When I play the video in the editor it runs very very slowly. Sorry if this is a dumb question so be gentle. Thanks