GUIButton Standard Texture?

Hello !!
If i create a GUISkin there’s a standard button texture. as i inspected it and saw no real texture attached. there is a very small… something. The Question is how can i make similar ones? i mean the GUIButtons are quite cool but sometimes i want them in other Background colors or a little less transparent or something like that and i wanted to ask how i can make such own button textures !!

I’M not really good in designing textures or… designing anything.

i really hope you can help


Here is the link where you can download unity official GUI skins
Then you can change color and customize them in photoshop or any other software( GIMP or even paint).