Customising a Theme

Folks,
I am a Newbe and an absolute novice at this.
I am trying to start blogging and have chosen a Theme for my Word Press site. Whist trying to relocate an image on the home page I screwed around with;
/* Twitter Link */
#twitter-link {
display:block;
position:absolute;
right:10px;
top:59px;
width:151px;
height:47px;
background:url(images/twitter-link.png) no-repeat 0 0;
}
and ended up getting the following “message” on my home page;
FW-1.3

When I try to reedit back to the original values for “right” and “top” nothing changes.
HELP PLEASE!!