first step with blender - need help with sequences

hello,
i am now for about 20 minutes a blender user and managed to make a fbx-object of a rotating cube (the default one).

now the question:

i defined 75 frames long sequence with start and end position (rotation).
the timeline is 10 sec by default.

but: even when i shorten the timeline (the round button on the right end), the exported sequence , when looping, is always 10 seconds long.

how can i adjust the overall length of the sequence? so that the loop start inmediately?

thanx stan

problem solved: under 'dimensions / framerate there are edits for start & end frames of the sequence. now it works.

regards stan