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The words at the top "Just Use It" are the site's slogan. You can change it by going into your admin section Preferences-->System-->General Settings.
When you get to that page, you'll notice on the second line "Slogan for your site." To the right of that, you'll see "Just Use It." You can change that to whatever you want it to say.
If you want to get rid of it completely, look for this tag in your theme.html <{$xoops_slogan}> and just remove it.
I need a little more description about how you want to place the words you intend to have next to your logo.