Can I create a button?

I would like to make a simple "Submit" button (not just showing a link but having some kind of simple graphics automated).

Are there a any ready made styling in the template for this?

There is a .button and .bigbutton class created for this purpose, but if This design is not enough, You can use override.css to create your own buttons.

Great! Can you please give a short instruction on how to implement it?

What exactly?
How to add class to an anchor link or create new css declaration?