Slider Size

Hello,
I want to have the nivo slider appear below my navigation menu and the main, white body containing text on my home page. I can’t get the images to be smaller than taking up most of the page, when I “turn on” the Nivo slider, despite resizing the photos before uploading. How do I set the size and position of the of the novo slider? Or is there a better option for achieving this look?

Thanks