Ed_Hika wrote: ... teach me how to investigate the class name ... then I will not need to trouble you for small queries like this.
Good point! So, let's skip the rest and get you going with finding out ID's and classes, because that and CSS is all you need for styling the buttons.
The best tool, as also mentioned in the documentation here, is Firebug, a free extension for Firefox. After installation, simply right-click on an element (i.e. a button), then select "Inspect Element with Firebug". The rest you'll find out quickly, or read about elsewhere.
Other browsers offer similar tools, sometimes already on-board, but hardly anything works as well as Firebug.
In addition to this, the search function here on the forum works wonder, too. You'd find the answer to your main question many times all over the place already...