I don't have Photoshop, so I used Affinity Photo for this project. The process of creating a brush is different, but the results are similar.
I created an Image Brush from a watercolour texture swatch and used the brush to create a background for text. I experimented with colour overlays and blending modes to achieve this result:
I did the brush class by Sandra Bowers at the same time as this one. You can see my project there at this link: https://www.skillshare.com/classes/design/Add-Digital-Textures-to-your-Illustrations-with-your-own-brushes/1439371106/projects/83439?via=class-details-projects-page