Make gradient tune as poster background image

Quick answer：

Creating a gradient tune as a poster background involves using graphic design software to apply a gradient color scheme to the background of the poster. The gradient tune can be designed to have a smooth transition between colors, often used to evoke emotions or create a specific atmosphere. To do this, you would select a gradient tool in your design software, choose the desired colors that represent the tune, and apply the gradient to the background layer of your poster design.