Lets start with a new document, sized 1200 x 1600 px. Press D to set the default palette colors as Foreground Black & Background White. Press Alt + Backspace to paint the background black.
Above this make a new Group, and name it ‘clouds’. Set the group Blend Mode to Normal and set the Opacity to 75%
Within this new ‘clouds’, Group make a new layer . Select the Gradient Tool(G) and apply a linear gradient going diagonally. Use the colors Orange (#fd7c00) and Purple (#6f156c). Reduce the opacity of the layer to 65%.