Textured Lines with Pen

I've got an image, and I'm trying to draw some lines with the pen tool. A plain line looks "odd" and I need to have some "texture" to the line.

I found some info about drawing the line, then going to style, and selecting brushes and it would apply the texture. I've got the line, and on the right panel "Layers, Channels, Brushes, Stock" I select "Brushes" and select a texture. It doesn't apply.

I've been searching for some video tutorials, since the steps I'm seeing don't seem to match what I'm seeing.

I'm using Affinity Photo 2.6.3 on PC.

Is this possible? Am I just looking in the wrong place?