One of the key features of the Spectra template is the slideshow that you see on the front page. This is actually a module position in the template called "Slides". Slide Show SP2 Module Parameter Settings are described here. You can see the settings of width and height for this slideshow in the screenshot below.

For image and text you must have a category. At least 3 Articles with images have to publish under this category The Image width and height will be 451px and 314px. Then select actual category from Data Source option .

Then fix some settings from Data Source option.

Layout must be Default from Slideshow Options.

Click No from Navigation Options> Show Arrows