The Theme Options panel is available in PRO version.
The Photostat Lite is a free WordPress theme build in WordPress customizer whereas the Photostat PRO theme is built in more user friendly Theme Options panel. The PRO version contains lots of sections in home page for creating beautiful and professional website.
To customize this free theme, first create all pages for slider, services and welcome section with Featured Image
Then Go to the Appearance -> Customize -> Theme Options Panel -> Slider/services/welcome -> Select Page
Please check the documentation