Addings dust in the air?

How would i go about doing this:

Im presuming its a particle effect?

Create a brush with tools/toolstrigger texture, press control+T, click into the dropdown item on the window, select func_dustmotes, and adjust values for your liking.

Thanks, also instead of starting a new thread, how do i make blend textures, i need a dev to grass blend, should i request here or Modeling/Skinning thread?

Create your own vmt

    "$basetexture" "grass"
    "$basetexture2" "dev"
    "%tooltexture" "grass"

Replace grass and dev with the texture names

Im new to making textures so;
What do i do with the code you gave me, also will I need to include it in the BSP, or is it not classed as a custom texture therefore it won’t be pink and black?

You should include it.

The code is for textures.
You can read up more on it if you need.