Simple Font Change Info Needed

1st post on this forum. I’m a very, very recent convert from Joomla. Just finished my first basic site design in WP. I have a quick question about changing a font in a plugin. I used Yoko free theme http://wordpress.org/extend/themes/yoko and added Fast Secure Contact form http://wordpress.org/extend/plugins/si-contact-form/. I can’t seem to locate how to change the font in the plugin to get it to match the theme perfectly. From what I can tell the theme font is Droid Sans. Could someone please walk me through how to get the font the plugin produces to match the one the theme produces? Thanks for your time.