I think you got a bit confused, 09:18 Guest. The line "ad-free search engine with search suggestions" refers to the search engine
Dumb Search, owned by the user dumbsearch.
DuckDuckGo is not promoted as being ad-free - there's even the message "ads via..." under the ad in the sidebar.
Maybe you could clarify what that line in your signature refers to, dumbsearch?
Here's a good tutorial on how to insert an image into your Yahoo Mail signature:
http://email.about.com/od/yahoomailtip1/qt/How_to_Insert_an_Image_in_Your_Yahoo_Mail_Signature.htmI would suggest just using these buttons to link to the DuckDuckGo homepage, since the homepage already has a "Add to [name of user's browser]" button that links to the different DDG browser plugins.
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