Find the font you like to use at:
http://www.google.com/fonts/
I choose Tangerine
. . . . . . . . . . . . . . .
Edit HTML of your template
Ad this code just after <head>
<link href="//fonts.googleapis.com/css?family=Tangerine:400,700" rel="stylesheet" type="text/css"/>
find:
<Group description="Tabs Text" selector=".tabs-inner .widget li a">
<Variable name="tabs.font" description="Font" type="font"
default="normal normal 14px Arial, Tahoma, Helvetica, FreeSans, sans-serif" value="normal bold 26px Tangerine"/>