Size of the slider

Hello,

there is a concept i don’t understand with adding photos. For example, I have a folder of 40 photos in 640×480 format and I want to make a simple photo carousel. To do this I add a slice and I choose image and I select the 40 photos. So I have 40 slices with a background in each slice. Even if I chose slider size at 640 x 480 the carousel is displayed full page and distorts the images naturally. How to make sure that the size of the slider is 640x 480 and not full width?
The other way is to choose the Blank option and add image by image in the 40 slides. And naturally to make a carousel with the base of WordPress (but I want to use Smart slider free for the moment).

I hope I have been clear.

Thank you