How do you create designs for watch face

I’m new to this and I saw alot of designs that are very neat… how do you design a face for your watch

What die you mean , how ? Just try the creator(in your Browser on your pc/Mac) and Play with it. If you want to make more creative Designs you can Upload Images from your pc. So you can Design stuff in Photoshop or Gimp or whatever and Upload it, to combine it with the given tools.
Another Trick , sometimes you can Click how is it made under the Designs you like and than you can See how its Made in the Editor.