Quad with fuzzy painted wall-like edges

Hello,

I am new here. Glad to join the community!

So I was told to learn to create adjustible-size rectangles with fuzzy torn edges (when painting a wall) with single color but non-uniform irregular background, with an ability to scale to an ordinary size (to fit any amount of text in there).

Here is an image with desired result:

Please tell me what tools should I use and general steps to achieve this effect?