if by sprites you mean frames... well that is an animation issue, nothing to do with construct.
generally the more frames or "tweens" (meaning in between key frames) you have, the smoother it will be, but it will also change the speed. However you can adjust the speed of the entire animation by changing the speed parameter on the right in the Spite Editor.
To figure out how long an animation will run you take the number of frames divide it by the speed.
i.e.: you have 6 frames running at 13 speed. The entire animation will take 6 / 13 = 0.46 seconds
4 seconds will be a lot of frames to draw. generally most of my animations run around a speed of 13. So that would mean making 52 frames...
but it all depends on what you are trying to animate!