Hello dove, I just found your wonderful stock here and honestly im just a beginner in illustrator, I know that these patterns can be used in my illustration but how would I go about applying to my art?
Yeah you can either double click the brush in the brush pallet to bring up the pattern brush options dialog (this will change all instances of the brush) or click the "Options of selected object" button in the brush pallet (this will change just the options of the brush you have selected).
I just saw a tutorial from Dave Cross on using Illustrator patterns in Photoshop. If you have Illustrator you can drag the swatch out on to the artboard and then copy and paste it into Photoshop (File>New - use clipboard preset). After that go back to Illustrator and select the path that is used to define the pattern. It will be an un-stroked un-filled path in back of the pattern. Copy it and paste it into the Photoshop document and then create a selection from it. Click on the layer with the pattern and click >Edit>Define Pattern.
It works on most repeating tile patterns found in Illustrator. I've tried it and it works great.
If you want to use it in Photoshop, you can use the place command to place it as a smart object and then rasterize it for use as a brush or shape. It's mean't for Illustrator because it's a pattern brush that you can apply to a vector stroke and it will seamlessly repreat.