No one has helped me on the last two questions. This site used to respond when others asked for help.?

At some point I must have become a member of Microsoft Windows XP. When that program opens my computer the first screen demands my user name and pword before I can even get to my home page. I really need to delete this page for good but, being a computer illiterate with the IQ of a kumquat, I don't know how to do that. Please help.