Few Questions By Newbie

First things first.  I am brand new with Dolphin, and am just starting my learning process, so please bear with me and my stupid questions.  

How do I change the words at the top of the page

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to my site name and slogan (without having to upload a new logo)

thanks in advance

That isn't text, it's actually part of the logo grafic... so uploading a logo of your own or removing the logo section from the template completely would be the only way. 

You can upload a new logo from Administration -> Settings -> General Settings.  Remember to uncheck the resize box under the upload field, or else you're going to have a bad time.

realizing you are new, wont pound on you too severely, the questions you have asked, have been asked sixty-seven-katrillion times, the answers to most of your required acclimation inquiries are on this site, you just have to search, and i dont mean single word search, you need to be specific with what you are searching for, and most likely you will find an answer.