Heidi not easy to explain how to make it smaller as almost everyone has different software running. All cameras come with their own software disc and each different from the other. However all will have a Resize option. I have four different camera softwares setups running and all have a resize option...and its quite easy to do when you find your Resize area.
Some have infinite resize options and some have standard ones like
320 pixels x
440 pixels x
640 pixels x
and so on
Good luck