Problem with Slider and Latest News

I’m new to wordpress, using the Firmness theme and have problems with using that Slider. I selected a cetegory of images for the slider and in the preview it shows that properly, but when I click “Svae and publicize” somwthing goes wrong and the slider disappears. There is only a white space instead of the slider.. the same happens with the “Lastest news”. What should I do ? Thank for all the responses