Where to find paper background, and how to make the texture show under the drawing

THIS IS NOT MY ART- credit to the amazing Sam Larson.

I have been unraveling the secrets of procreate for about a year now and really getting the hang of it. I desperately want to achieve this style.

I recently purchased Sam Larson‘s brush set (artist pictured here) but it does not include the paper background, and the brushes do not create the texture of paper showing through. That’s what I love most about this style, it looks so hand-drawn and authentic.

Can anyone explain to me 1: where to find the paper background, and 2: how to achieve that texture through my brush set?