You are using the free version of Amplitude theme. The Theme Options is not available in free theme. The Amplitude PRO theme is build in user-friendly Theme Options Framework.
To display image slider in Amplitude Free theme
– Create the pages for slider from WordPress dashboard
– Slider Title managed from page title
– Slider image managed from page featured image (slider image size 1400 × 600 pixels)
– Go to Appearance -> Customize -> Theme Options Panel -> Slider Section
– Select the pages from dropdown for slider