Custom Menu with Images

Hi,

I am new to word press and the css world. I need help in customizing my “custom menu” as you can see by my website (http://www.fefesfix.com) I have a menu on the right side, with the links about fefe, facebook and news. I want to turn these 3 links into images that I have already uploaded to the twentyten images folder.

How can I change this?

Thanks in advance!!

PS: I am using the custom menu widget