Change root directory

Hello dancedhall, Sorry for the clarity. For example, if the directory of my laptop would be like this "c:\documents and settings\administrator>", just I want to replace it with my name. Don't forget that windows is found in drive c, or, in other words, when I opened the command prompt, it starts with the default directory, which is "c:\documents and settings\administrator>". So this is what I want to change. I'm poor in English, it is my third language. Thank you.