slider image size

Hi,

I am new to wordpress and I am using theme pinboard. I have inserted a gallery, full size, type slide show. I expect to see a full size slide show as it’s shown on the image of the pinboard theme (the morning latte) But I get get is a small image inside the slide show with a large margin on the sides. I am not sure how to make the slider full size with no margins.
thank you in advance for your help.